Q&A Trademarks

How Can You Know if a Trademark Search is Reliable?

There are different situations where a trademark search is beneficial. And there are different types of searches with different levels of scope. But how can you know if a given trademark search is reliable? How thorough or extensive does search have to be? Are simple queries in online portals enough to rely on? This article will address those questions about what makes for a good trademark search.

Overview of Best Practices

Trademark searching is perhaps more art than science. There is no single approach suitable for all situations. But there are a number of factors that tend to make trademark searches better and more reliable in general. These include the following:

  • Accounts for applicable trademark laws in the relevant jurisdiction(s)
  • Encompasses variants and similar marks, and not limited to exact or identical matches
  • Looks beyond identical and overlapping goods and services to different but related goods/services
  • Uses reliable tools or databases with relevant content coverage
  • Results are coupled with a competent legal analysis

These factors are discussed further below. Although this article is not meant to be a tutorial on the mechanics of or strategies for performing trademark searches.

The Likelihood of Confusion Standard

Under U.S. trademark law, a likelihood of confusion standard is used. It applies when determining if a proposed mark is federally registrable. This is the standards trademark examiners apply to new trademark applications. Registration will be refused if there is a likelihood of confusion with a prior mark. It also generally applies when assessing potential infringement. Trademark infringement arises when there is a likelihood of consumer confusion, even if actual confusion has not occurred among customers.

This legal standard looks an multiple factors from the point of view of relevant consumers. There is no precise formula for how these factors are applied. But two factors tend to be most important. One is how similar (or dissimilar) two marks are, when considering the overall commercial impressions the proposed create. Another is how similar (or dissimilar) the goods and services are.

Importantly, the trademarks do not have to be identical to be similar enough to create a likelihood of consumer confusion. The goods and services can potentially differ as well. For instance, they might partially overlap or the goods and services might differ but still be considered related. There is no universal, bright-line rule for how close is too close, or what sorts of differences will sufficiently avoid potential confusion.

Legal standards in other countries may different. But most countries take a generally similar approach.

Simply Queries Are Often Not Enough

A reliable trademark search needs to be broad enough to capture different but similar marks. This includes things like alternate spellings, phonetic equivalents, transposition of words, different punctuation—like the difference between one word or two, with or without a hyphen—and even other words with similar meanings. Foreign-language translations or transliterations might also be considered, which can be particular useful when looking at foreign countries where other languages are common. Basically, the search needs to account for the fact that prior trademarks may be relevant to the likelihood of consumer confusion even though they differ in some way.

A few limited keyword searches in an Internet search engine or trademark database may not be sufficient. That is especially true if searching only for marks that are identical. For instance, if a search for a proposed brand name that includes the word “theater” omits prior marks using the alternate spelling “theatre” or intentional misspelling “theatr” it could miss something important. The same goes for portmanteau or compound word terms that incorporate words like “theater”.

Trademark searching also involves the difficult problem of trying to prove a negative. You can never be absolutely certain that nothing relevant is out there. If nothing appears it might mean nothing else exists, or it might simply mean you missed a relevant prior mark. A perfect search is impossible. Even a high quality search might miss a prior mark that someone else considers relevant. After all, there are some judgement calls involved with these fuzzy legal standards. But the goal is to use sufficiently robust and thorough searching methods. Getting “zero hits” or “no results” from a few cursory searches, based only on looking for exact matches in a limited coverage database, is often not adequate or reliable.

Using Online Portals

There are some free, open-access online portals that allow trademark searching. Some of these are provided by official trademark offices. Others are privately run by various companies. There are also proprietary databases that require paid subscriptions or other fees.

Many free “trademark availability” search engines are unreliable and misleading. For instance, queries in a free trademark availability search engine for the following proposed marks all said they were supposedly “available”:


Of course, none of these proposed marks are actually available for use, at least not if they create a likelihood of confusion with the famous brands they incorporate (or cause dilution). Simply adding an additional generic or highly descriptive term without changing the overall commercial impression is not enough to avoid confusion. Those minor differences from an existing mark generally do not mean that a proposed mark is available for use or registration. Any of these example marks would be refused registration. Their use would probably also result in legal problems.

Adequate Coverage

A trademark search also needs to encompass sources likely to contain the kind of trademark information that matters to your legal questions. There are many different trademark databases available. But there is no single comprehensive database of all worldwide trademark information searchable across all possible fields. It would be nice if there were. But every real-word tool or database has limits on its coverage. This even applies to general-purpose Internet search engines. For instance, there can be purely offline trademark uses that cannot be found online.

Reliable searching involves selecting the right resources to consult. This might mean paying for access to certain proprietary tools. Or it might mean searching in multiple databases or tools each having different coverage. Often the specific coverage of a given database can be confusing or not readily apparent.

Considerations for Graphical Logos and Non-Traditional Marks

Searching trademarks with prominent visual design components or stylization, especially logos without any wording, presents some unique challenges. The same applies to non-traditional marks like trade dress, colors, sounds, etc. There are tools that allow what amounts to a reverse image search of a logo. Those tool can be helpful. But they are not always completely reliable on their own. There are also design search codes or other classification systems for categorizing elements of trademarks other than wording. These codes or classifications offer a particularly helpful way to search for similar logos, visual design elements, and elements of non-traditional trademarks.

A Search Alone is Not a Legal Opinion

Simply searching for trademarks—and no more—tells you very little. It will at most give you a list of existing marks. But which of those matter? Which ones are distinguishable? Which ones are close enough to present problems? Was your search robust enough to have confidence that there actually are no problematic existing trademarks? To answer those questions you need a legal opinion. That means analyzing trademark search results from a legal perspective. It is recommended to have a knowledgeable attorney analyze search results and provide legal advice about registrability and/or any infringement risk.


There is definitely cost associated with a quality, reliable trademark search and accompanying legal analysis. Costs especially tend to increase when the scope of a search encompasses more geographic regions or jurisdictions. Selecting the cheapest option, or taking a free do-it-yourself approach, often does not result in the reliable results. Cheap searches and $99 fixed-fee “legal” services are not going to give you a reliable legal opinion or provide meaningful strategic guidance.

Small businesses frequently feel they cannot afford these costs. Skipping a search means you are taking you chances. It is like rolling the dice and hoping there are no obstacles or infringement risks lying in wait. Businesses often regret not clearing their branding before adopting it, or regret selecting a weak mark. Doing so might mean later facing large re-branding costs, limits on expansion of your brand, and/or a decreased business valuation. In a worst case scenario it might even destroy everything built-up in a business. So a good search (+ legal opinion) upfront can be a good value in the long run.

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Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.

Q&A Trademarks

How Should a Trademark Search Be Conducted?

What should a trademark search involve? How should a trademark search be conducted? These are questions about the scope and format of a trademark search. There are many different ways of performing trademark searches that vary in scope and thoroughness. Not all searches are equal. The right approach will depend on a number of factors including the purpose of the search and the type of legal questions the search is meant to address. The following is an overview of basic considerations about how to structure a trademark search to meet your needs.

Different Types of Searches

Sometimes trademark searches are grouped into different levels, with different pricing. A basic search is sometimes called a “knockout” search. These are usually the cheapest option. Names like “comprehensive” are applied to other types of searches that are more thorough (and more expensive). There are also special searches for various specific purposes, such as to look for evidence of relatedness of goods and services. But what differs between these different searches in terms of what you get? And which one is the right choice for your circumstances?

Knockout Searches

A knockout or preliminary search is usually the most basic and most limited in scope. It is typically limited to searching only registrations and pending applications in a particular jurisdiction. This means it will not capture unregistered uses of similar trademarks that may exist.

Also, a knockout search may be limited in terms of capturing variations. Trademarks do not need to be identical to create problems under the likelihood of confusion standard. The exact scope of knockout searches can vary. But often they will provide little or no identification of alternate spellings, phonetic equivalents, translations, distinct terms with a similar meaning, or the like. Yet prior trademarks that are not identical can still create a likelihood of confusion in some situations.

If a knockout search is all your budget permits, it may be better than nothing. But often a knockout search is often too limited to provide a lot of value. For example, for a trademark clearance or freedom-to-operate in the United States where unregistered “common law” trademark rights can exist, a knockout search is generally inadequate. And even for merely preliminary purposes some “bargain” searches may fall short. Quite frankly, cheap searches are not always reliable.

More Comprehensive Searches

A more comprehensive or full trademark search is usually just what the name implies. It is a broad search meant to capture as much as is feasible within a reasonable budget. More comprehensive searches will typically assess any unregistered prior uses. These searches also usually devote much more effort toward searching for alternate spellings, phonetic equivalents, and different words with similar meaning. But beyond those typical parameters, the exact scope of these searches can still vary. There is a continuum of effort involved.

For example, sometimes, but not always, they will address registrations in U.S. states, territories, and districts too. For marks used only locally, and not in interstate commerce, such a state or similar registration might be the only type available. Searching all such state-level registrations can add significant extra expense to a search and therefore is frequently omitted.

Also, whether foreign words are searched will also vary considerably. There are many languages and whether wording of a proposed mark would be considered relevant to one with a similar meaning in another langue is very context-dependent. It can matter if the other language is commonly spoken in a relevant area. For these reasons, translations will usually be considered like separate searches and excluded from even fairly comprehensive searches.

Special Searches

There can also be other types of trademark searches meant to address very particular questions. For instance, there can be situations during the examination of a trademark application or in connection with a lawsuit in which certain trademark searches are useful. These can include searches for evidence of relatedness of goods and services, by looking for usage of a single brand with different but “related” goods/services. Also, trademark-related searches might be performed to identify evidence of genericness or of descriptive meaning of the the words of a given mark.

Geographic Scope

Every trademark search should consider the particular jurisdictions of interest. That is because trademark rights are territorial. They exist only in in particular countries, states, or blocs (like the European Union). For example, there might be pre-existing trademark rights in one country but not another. A search for trademarks in one country will tell you little or nothing about trademark rights in other countries.

If new branding will be used in multiple countries or geographic regions, a trademark search (or series of searches) should encompass each and every one of them. Even if a trademark will not be used in other regions immediately, if expansion to them is likely or merely possible in the future it may help to search those countries too. This can allow evaluation of possibilities for later geographic expansion. This avoids being boxed-in and finding later expansion stymied.

For very substantial brands, with large advertising campaigns planned, it may also be worthwhile to search other jurisdictions to identify potential priority claims. This is because an international treaty may permit an application to be filed in a country of interest that claims priority to an application filed in another country up to six months earlier. In other words, this means searching in countries beyond those you plan to use your mark in. Although this sort of step is often skipped due to the effort and cost and the relative infrequency of such priority claims causing problems.

The type or scope of searching that fits your needs will depend on the nature of the proposed use of a trademark and the particular legal questions you want to address. And your budget. But bear in mind that a search alone tells you little or nothing unless the search results are analyzed by knowledgeable trademark counsel. It is all too easy to misunderstand the significant of bare trademark search results if unfamiliar with trademark law. You need a legal opinion too. Running a few queries yourself in a trademark database and (supposedly) getting “no results” may only provide false confidence.

Another way to think about all this is to ask, “How difficult would it be to later re-brand later?” If the answer is “difficult”, then a broader and more thorough search and analysis is worthwhile. When you are not well positioned to pay legal fees to defend yourself against infringement allegations, or just the thought of having to do this later seems unpleasant, then a search is one way to try to reduce those risks upfront. These things point to doing more than a cursory knockout search. Yet a slogan or tagline might be easily dropped or changed in some situations, unlike a primary brand.

More limited searches are better suited to low-stakes situations. For instance, when you are only concerned with registrability in the short term, such as for a planned intent-to-use (ITU) trademark application, then a knockout search may be minimally adequate. During examination of new U.S. federal trademark applications, the U.S. Patent & Trademark Office (USPTO) only looks at prior federal registrations and pending applications. They do not search for unregistered “known marks”. So a knockout search is similar in scope to searching done by a trademark examiner. But a knockout search will usually not provide a very good picture of all possible oppositions or cancellations sought by others against your desired trademark registration.

Have a Backup or Alternate Mark In Mind

It is quite common for a trademark search to reveal a potential problem with a proposed mark. For that reason, it is often helpful to conduct searching against a list of multiple candidate trademarks. These could be ranked in preferential order. Having a list of multiple marks searched and then legally reviewed in parallel or in preferential sequence increases the chances that at least one of them will be available and registrable. This can be especially beneficial when clearing a mark planned for use in many different countries or regions.

Of course, working from a list of multiple candidate trademarks makes the most sense before you have committed to certain branding. That can be challenging for many businesses. There is a tendency to grow attached to desired branding. But the pain of giving up on a favorite only gets worse if you have to re-brand later because of a problem.

Caution: No Search is Perfect

No matter how thorough, no search can eliminate all risk when selecting and adopting a trademark. Searching is always imperfect and can only serve to minimize risks. Trademark rights in the United States arise primarily from use and not mere registration. So it is possible that someone is using the proposed mark (or a similar one) in connection with the same or similar goods and/or services, but that use may not be detected in the search. That could be because the prior user did not seek registration or a prior mark was not listed in any of the resources or databases that the searcher used.

Also, when it comes to the analysis of search results, there can be differences of opinion. A prior user or registrant noted in this search may object to use or registrations of a proposed mark. Such objections may be questionable or even baseless at times. That is sometimes called trademark bullying. Or there may be facts that influence the ultimate outcome of a dispute that the searcher or attorney was not aware of.

The main takeaway is that just because a search does not identify any problems does not mean that an infringement allegation or refusal of registration is impossible. The right search and a competent legal analysis can still be quite useful and valuable.

Photo of Austen Zuege

Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.

Q&A Trademarks

Do I Need a Trademark Search?

When adopting branding, such as a brand name or logo, people sometimes wonder, “Do I need to conduct a trademark search?” Or, “Is this trademark available?” These questions can arise when considering filing a new trademark application. Or they can come up when adopting branding for new products or services being offered for sale. In either context, this question should be considered at some level. What follows is more detailed information about whether and when a trademark search is worthwhile. Another article covers how to structure a trademark search.

What a Trademark Search Can Tell You

Some brand names and logos are already taken by others. In fact, it is quite common that when you have a “great” branding idea someone else has already had the same idea or a similar one. A trademark search can help address either or both of the following questions:

  • Will proposed branding create a significant risk of infringing someone else’s existing trademark?
  • Will a given proposed trademark be registrable?

The first question is about trademark clearance or freedom-to-operate. It is about assess risk and trying to avoid infringement problems and disputes. The second question is about whether a given jurisdiction is likely to grant you a trademark registration. It is more about how protectable a proposed mark appears to be. Put another way, the second question can inform you about the scope of exclusivity potentially available under the proposed mark. But both questions are about trademark availability.

A single trademark search in a given jurisdiction can generally be used to analyze both of these questions. So one search should permit both legal questions to be addressed. But the scope and thoroughness of a search can vary.

What a Trademark Search Won’t Tell You

In the strict sense, simply searching for trademarks tells you very little. It will only produce a list of existing marks. But which of those matter? Which ones are distinguishable? Which ones are close enough to present problems? Also, simply obtaining a list of prior trademarks will not tell you whether a proposed new mark is distinctive enough to serve as a trademark. And a search alone will not address other strategic considerations involved in trying to register a particular trademark.

After obtaining search results, it is necessary to further analyze whatever comes up in a search from a legal perspective. Anyone who does not understand trademark law will struggle to properly interpret what is or is not a problem when it comes to infringement risk and obstacles to registration. Self-serving bias is a common issue too. When you have a great branding idea, you might be biased against the notion that someone else already has a trademark that presents an obstacle to your business plans. This can turn into a matter of unreasonably splitting hairs over illusory differences. Or it can lead to incorrectly disregarding inconvenient or disappointing search results.

It helps to have a knowledgeable and independent expert analyze search results and provide guidance about registrability and/or any infringement risk. This kind of legal analysis goes beyond searching alone.

Which Region or Regions?

Trademark searches should be considered for each relevant region. That is because trademark rights are territorial. They exist only in particular jurisdictions, that is, in particular countries, states, or blocs (like the European Union). For example, there might be pre-existing trademark rights in one country but not another. If new branding will be used in multiple countries, a trademark search (or series of searches) should encompass all of them.

Is a Search Legally Required?

In the United States, it is not required to perform a trademark search before applying to register a mark. So, it is possible to proceed without a search and take your chances. But it is a gamble.

But, on the other hand, investing considerable effort and resources into developing and advertising a brand only to find out later that it cannot be protected may lead to crushing disappointment. And it may result in wasted time and money. Having to rebrand later on after a problem arises is usually far more expensive than the cost of an initial search and analysis. On top of that, legal liability and even merely a cloud of uncertainty can have a terrible impact on a business, from disruption of daily operations to decreased valuation.

An early trademark search encourages adoption of a non-infringing and registrable mark from the start. The cost and burden to switch marks or re-brand generally increases over time. So even if a search is not mandated by law, obtain one along with a legal opinion still offer pragmatic benefits. Those steps can potentially avoid a lot of later headaches.

Didn’t I Already Take Care of This?

You still want a trademark search despite having registered a company or assumed name with a local government. The same goes for having already registered a domain name containing your trademark. The fact is that practically no screening is performed by the government or a domain registrar. They only care about such names having the slightest differences. Corporate filings and domain name registrations are accepted when there are only minor differences in terms of punctuation or a single different letter. That is not enough to avoid trademark problems. Trademark confusion and infringement (and/or cybersquatting) is still possible in those situations.

Small businesses often mistakenly believe that corporate and domain name filings insulate them from legal problems like trademark infringement. But they don’t.

When is a Search Needed?

In terms of timing, a trademark search should be performed before any new brand is adopted and used. In other words, the ideal time for a search is before you commit to a particular trademark and before you start actually using it. But searches can still be worthwhile later on. For instance, as usage changes to encompass different goods or services, or expands geographically, new issues might arise that call for a new or further trademark search. Special types of searches may also be useful during examination of a trademark application or in connection with a contentious proceeding.

Further, a trademark search is just snapshot at a given moment. Use of similar marks by others is constantly changing. Prior registrations are abandoned or cancelled, commercial usage changes, consumer perceptions evolve, and new brands are adopted by others. This means that trademark search results can go stale and lose relevance as time passes. Ideally, a trademark search should be performed close to when business and marketing decisions are made about the mark being searched. Old search results may not be reliable for a legal review much later in time.

Photo of Austen Zuege

Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.

Patents Q&A

How Can I Find Patents with the USPTO’s Patent Public Search?

The U.S. Patent & Trademark Office (USPTO) makes granted U.S. patents and published U.S. patent applications publicly available. Patent Public Search is its open-access patent searching platform, available online to anyone free of charge.  It exists with two different interfaces:  Patent Public Search Basic (PPUBS Basic) and advanced search. Both allow U.S. patents and published applications to be searched simultaneously. Coverage is limited to only U.S. patent documents.

screenshot of Patent Public Search landing web page
Screenshot of the USPTO’s Patent Public Search landing web page, with links to the “Basic Search” and “Advanced Search” interfaces

There are official training guides and frequently asked questions (FAQs) available for Patent Public Search. These provide detailed guidance about how to use the tool, particularly the advanced features. What follows are basic explanations of how to fetch individual patents from the USPTO and find either PDF images or selectable/copyable text from U.S. patents and published applications.

Screenshot of the USPTO’s Patent Public Search FAQs

Some information about how to structure and perform patent searches is available in the article “Patent Searching: (Almost) Everything You Need to Know” and in the book Patent Freedom to Operate Searches, Opinions, Techniques, and Studies.

Using the Basic Search Interface

The Basic (PPUBS Basic) search interface allows granted U.S. patents and published patent applications to be fetched by number (“Quick Lookup”), and allows some keyword-based searches (“Basic Search”). But it returns only PDF copies. 

Screenshot of the USPTO's PPUBS Basic search interface
Screenshot of the USPTO’s PPUBS Basic search interface

This interface is simple and mostly self-explanatory. Although, if desired, consulting the USPTO’s basic search interface overview may be helpful. One important thing to note is that the search input fields allow only a single word or number in each and a maximum of two keywords can be used. So, for searches using two distinct keywords, it is necessary to use different input fields for each of them and to select a Boolean operator (AND, OR, or NOT).

Screenshot of an example search result for a “Quick Lookup” of U.S. Pat. No. 10,000,000 via the USPTO’s PPUBS Basic search interface

The Basic interface is most useful for fetching PDF copies of granted patents and published patent applications when the patent or publication number is known. The trade-off is that its functionality is rather limited for subject-matter searches and “full text” is not available for returned results.

Using the Advanced Search Interface

As the name implies, the advanced search includes much more advanced search functionality than the “Basic” interface.  However, the advanced interface is highly esoteric and non-intuitive. It may not even display properly on all computers. For instance, primary the input field near the upper left sometimes appears hidden when the tool is opened on computers with small display screens, like laptops. 

Screenshot of the USPTO’s Patent Public Search Advanced Search interface, showing the results of a search for U.S. Pat. No. 10,000,000 using the “.pn.” field code

The Advanced Search interface allows queries of up to three distinct databases simultaneously:

  • US-PGPUB — containing U.S. pre-grant patent application publications from March 2001 onward;
  • USPAT — containing full-text granted U.S. patents from 1970 onward plus allowing classification and patent number searching from 1790 onward; and
  • USOCR — containing text-searchable optical character recognition [OCR] scanned pre-1970 U.S. patents

Fetching a particular patent or published application by number is surprisingly difficult with the “advanced” interface.  Use of the “.pn.” (for patent number) code is highly unforgiving and the period at the end is required. The USPTO has said it is possible to manually type in the URL and replace “00000000” with the desired patent number in order to reach it directly though an “external search”. Use leading zeros to fill a 7-digit entry if the patent number is 6 or less digits (for example, “0654321”). And do not forget the period at the end!  Unfortunately, Patent Public Search modifies this URL as displayed in a browser once it is visited so there is no simple way to bookmark it. Also, expect some frustration because these “external search” URLs do not seem to consistently work (especially if Patent Public Search was previously opened in your browser).

Annotated screenshot of Patent Public Search Advanced Search Interface "Document Viewer" “T / [camera icon]” button to toggle between text and PDF image views
Annotated screenshot of Patent Public Search Advanced Search Interface “Document Viewer” “T / [camera icon]” button to toggle between text and PDF image views

The advanced interface is currently the only way the USPTO provides “full text” of published patent documents.  PDF versions are also available by clicking the “T / [camera icon]” button at the top left of the “Document Viewer” panel that normally appears at the right-hand side of the screen along with the text (annotated in the figure above).  Toggling that button allows switching between text or PDF image displays of a given patent document. 

Other commands are available by clicking on rather confusing and esoteric icons in the “Document Viewer” panel, such as various quotation mark buttons that allow forward and backward searching of citations.  Note that references cited listed on the front page of granted patents are omitted from the “full text” display in Patent Public Search, meaning that “full text” is not truly available for all text of a given patent document. Foreign and non-patent literature citations will appear only in the PDF image of the granted patent and thus are not selectable to copy-and-paste them. 

Annotated screenshot of Patent Public Search Advanced Search Interface "Document Viewer" quotation mark buttons to forward and/or backward search U.S. patent documents from the "References Cited" section of a granted U.S. patent
Annotated screenshot of Patent Public Search Advanced Search Interface “Document Viewer” quotation mark buttons to forward and/or backward search U.S. patent documents from the “References Cited” section of a granted U.S. patent

If you plan to conduct extensive searching by subject matter, using keywords and/or classification codes, you may want to consult the USPTO’s official Patent Public Search training guides and FAQs as well as the “Help” menu tab inside the interface’s “Search Results” panel. The “Search Overview” Quick Reference Guide and the FAQs may be the most useful places to start, followed by “Searchable Indexes” (that is, field code) list and the “Help” menu tab inside the interface. Some content found in the “Help” menu tab of the “Search Results” panel inside the interface (such as explanations of proximity operator syntax) does not appear anywhere else at present—quite unhelpfully!

Also be aware that Patent Public Search uses search string syntax that is unlike commercial patent searching tools. Familiarity with other search tools (other than the USPTO’s old PubEAST and PubWEST tools) will not translate into any understanding of how to use Patent Public Search.

Alternatives: Patent Center, International Open-Access Tools, and Proprietary Tools

An alternative way to reach a particular U.S. patent or published application in USPTO databases is to utilize the Patent Center interface. Patent Center’s main interface provides a simple query field where you can enter a U.S. patent or published U.S. patent application number.  Once the results of a given query appear on screen, there are links available to the Patent Public Search text versions of the given published application and granted patent (if any) under Patent Center’s “Application Data” tab.  The button with the “T/[camera icon]” label can be clicked to toggle between a text view and a PDF image of the patent document in Patent Public Search. While navigating to patent documents through Patent Center requires many clicks, using it may be easier than using Patent Public Search.

However, links to patents and published applications in Patent Center are often broken or non-functional. This is a major problem. And Patent Center intentionally blocks copy-and-paste operations to copy patent or publication numbers into a different database that does function properly. The system has also been plagued by a lack of capacity. Rather cryptic error messages (usually colored red) may appear when attempting searches on the platform. These errors reflect that the computer infrastructure on which Patent Center runs has reached a capacity limit, forcing users to re-run searches. This can be seen as a form of under-funding the Patent Center infrastructure.

Another alternative for fetching PDFs of U.S. patents and published patent applications is to use a privately-operated site or a foreign patent office site with international coverage. There are many proprietary patent searching tools that require a subscription. But there are also open-access or semi-open-access tools available online that contain at least U.S. patent documents, including:

Compared to many other online patent searching tools, Patent Public Search has substantial usability flaws. Although it has more coverage and capabilities than it predecessors PatFT and AppFT, it is much less user-friendly and eliminated some features of the old systems. Tabbed browsing to open multiple documents at once is prohibited by the “advanced” interface, for instance. Also, the “advanced” interface frequently has long delays to load or fails to load, and the “basic” interface often stalls without loading patent PDFs—making them effectively inaccessible. These are faults with the USPTO’s computer infrastructure and the design of these tools. Even compared to other open-access platforms, like Espacenet, Patent Public Search is harder to use. It is even inferior in many ways to the “Delphion” tool from the early 2000s (which was converted into one of the leading proprietary platforms and is no longer open-access).

Proprietary searching platforms are still generally the best option. Although subscription fees will be prohibitive if you only perform patent searches occasionally.

Photo of Austen Zuege

Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.

Patents Q&A

How Should I Prepare an Invention Disclosure for Patenting?

If you are interested in patenting a new invention, or simply interested in assessing its patentability, a helpful early step is to prepare an invention disclosure. Such disclosures gather relevant technical information, as well as details about the identity of all potential inventors. The invention disclosure should be written and should further include drawings or other visual aids. It should be kept confidential. There is no “official” government form for an invention disclosure, though companies may have a form for internal use.

The following sample invention disclosure forms can be downloaded and used to document a new invention for patent purposes:

The main purpose of preparing an invention disclosure is to convey relevant detail details about the structure and configuration of the invention, how it functions, what is believed to be significant about the invention in relation to what has been done before (the “prior art”), and potentially other things that might affect the ability to patent the invention. This disclosure should be prepared by the inventor(s) themselves. It is usually not fancy or long. These sorts of disclosures are simply meant to gather basic, essential technical information and to point out what are considered the most important features. A patent attorney and/or patent searcher can then use the disclosure to gain an understanding of the invention in order to prepare a patent application or conduct a patentability search.

There may be additional documentation and information needed beyond what appears in an invention disclosure. Requests for more technical information are common. For example, patent attorneys will usually conduct at least one inventor interview to gather more technical information for purposes of patenting. But an invention disclosure is a starting point. Inventor interviews are much more productive if the patent attorney has some relevant drawings and other materials beforehand. That allows the patent attorney to have some sense of what the invention is about in order to ask better and more pointed questions.

It is important that an invention disclosure mention all the important features of the invention that might be patentable. Patent attorneys can ask follow-up questions, but they are not mind-readers. Omitting some major aspect of an invention on the invention disclosure entirely is a common mistake. Another common error is to focus on commercial marketability information, omitting technical details about what an invention really is and how it works that matter most for patenting.

An invention disclosure should also be relatively short and focused. While voluminous technical materials might have value for a patent attorney at certain stages of patent application preparation, it is inefficient for a patent attorney to read through dozens or hundreds of pages of such materials without some guidance. And an attorney might not fully or immediately appreciate what is new and inventive in merely “raw” technical data. An invention disclosure should be like a beacon pointing out what the inventor(s) consider to be most significant, at least as a starting point.

Invention disclosure forms that are signed and dated can sometimes provide useful records about who developed a given invention and when. Though a confidential write-up by itself will generally not preserve any patent rights—filing a patent application is required to do that. And there may be bar dates or deadlines by which a patent application must be filed.

Photo of Austen Zuege

Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.

Patents Q&A

When Should I Complete a Patent Invalidity Search?

There are many situations where it is desirable to challenge the validity or patentability of a granted patent or pending patent application. For instance, an invalidity search can be useful for an invalidity opinion to mitigate infringement liability, an invalidity defense in litigation, a proactive challenge to patentability at the U.S. Patent & Trademark Office (USPTO), or a pre-issuance submission (observations) to try to restrict or prevent a patent from being issued. But what is the best timing for such an invalidity search?

graphic of timeline for invalidity search

In one sense, an invalidity search is never strictly legally required. Though, practically speaking, invalidity searches are often crucial to avoiding or reducing liability for patent infringement in many contexts. These searches must be performed in a timely manner to obtain the greatest value from them. That includes performing searches in time to meet deadlines that require having suitable search results available.

Patent invalidity searches are reactive in the sense of being conducted in response to some infringement risk arising. That could be the receipt of a cease & desist letter, the filing of an infringement lawsuit against you, or other knowledge of a potentially problematic patent (e.g., via a freedom-to-operate study). In any event, an invalidity search requires first knowing which patent is the subject of the invalidity search. That is because an invalidity search depends on the scope of the particular claim(s) of concern and their effective filing date(s)—including any priority date(s).

It is a best practice to consider an invalidity search after a tangible risk of patent infringement comes to your attention. Knowledge of a patent coupled with a reasonable belief that infringement might be present can potentially give rise to enhanced damages for infringement. And knowledge of a pending patent application can potentially give rise to so-called “provisional rights” to pre-issuance infringement damages.

There may be deadlines that determine when invalidity search results are needed. For instance, in patent litigation in a district court, the court will issue a scheduling order that often sets a deadline to set for invalidity contentions. In is necessary to have search results available in order to formulate those invalidity contentions and prepare a suitable report. Other times, invalidity contentions might be requested through discovery requests, such as interrogatories. Either way, it is crucial to perform the invalidity search far enough in advance of such deadlines to allow for subsequent legal analysis of the search results.

Moreover, there are situations where a proactive challenge to a granted patent is desired. Proceedings such as inter partes review (IPR), post-grant review (PGR), oppositions, and the like may have various different deadlines by which a challenge must be filed. Such deadlines drive the timeline for completing invalidity searching. Just as in litigation, the search must be completed with time to spare to allow for legal analysis and preparation of any formal filing papers for the patent challenge, which may require considerable effort to prepare. Additionally, a pre-issuance submission (or observation) might be filed against a pending patent application and there likewise are both formal and practical deadlines to do so.

Lastly, if an opinion of counsel setting forth grounds for liability is desired to mitigate potential infringement damages, such an opinion should ideally be obtained before your relevant product (or process) is commercially launched. If patent in question is discovered only later, then such an opinion should be obtained without unreasonable delay. Having invalidity search results is a prerequisite to completing an invalidity opinion.

In all these possible settings, it is common for multiple invalidity searches to be performed. That can include follow-on invalidity searches performed in an iterative manner, in order to exhaustively locate prior art and to try to obtain sufficient prior art for desired (and reasonable) invalidity arguments as those arguments evolve and develop. It may also include searches performed by different searchers in different databases (including in non-patent literature databases), in different native languages, though investigation of prior public use and on-sale activities, and the like.

Have an invention you would like to patent? Have a brand you would like to register as a trademark? Concerned about infringing someone else’s intellectual property? Is someone else infringing your IP? Need representation in an IP dispute? Austen is a patent attorney / trademark attorney who can help. These and other IP issues are his area of expertise. Contact Austen today to discuss.

Patents Q&A

When Should I Complete a Patent FTO Search?

If you have decided to perform a freedom-to-operate (FTO) or “clearance” study to try to reduce the risk of patent infringement, it will be necessary to determine when a patent search should be performed. This is a question about best practices for the timing of patent FTO/clearance searches.

The following timeline provides an overview of major timing considerations and the best time to conduct a patent FTO study.

In general, the ideal time to conduct at FTO search is before a product (or technical process/service) is commercially launched but after its technical design parameters are sufficiently established to know what the search should encompass. That is a window of time in between an initial business case and the beginning of research & development (R&D) efforts, on the one hand, and the formal product launch on the other. Additionally, the FTO search and accompanying legal analysis should be completed well enough in advance of the product’s commercial launch date to allow time for possible risk mitigation efforts before infringement liability might start to arise. If the FTO search uncovers a potentially problematic patent, you gain the most benefit from that information if you have allowed time to take responsive action before a product launch point-of-no-return.

In this context, a product launch can be anything that is potentially actionable as patent infringement, including making, using, selling, offering for sale, or importing an infringing product in or into the USA. Though product launch infringement risks tend to be greatest when there is a major commercial release that makes the product (or process) widely publicly available, as opposed to mere preparatory efforts (such as prototyping) that might happen only on a private and confidential basis.

Having technical design parameters that are sufficiently established to know what the search is important. This allows the FTO searcher to understand what, specifically, should be searched—and what is excluded from the scope of the search. This process of determining what to search is referred to as “feature identification” (or sometimes “product decomposition”). This involves itemizing individual patent-sized technical features present in the product that are to be searched. But feature identification is only possible if there is sufficient technical information available. If R&D efforts are still in preliminary stages, or if there is really only a (non-technical) business case available, it may not be feasible to conduct an FTO search yet, or at least not for all planned product features. In those situations, a more generalized “landscape” search is perhaps more appropriate. Otherwise, the FTO search(es) for insufficiently-developed feature(s) may need to await further technical R&D.


After an FTO search is completed, there are various reasons why a later “update” search may be helpful. First of all, there is generally a delay of roughly eighteen (18) months between the filing and publication of most patent applications—and sometimes longer. This means that there may be relevant pending (but unpublished) patent applications that cannot be found during an initial FTO search. But, additionally, there may be changes to the technical design of planned or released product over time that merit further FTO searching and/or analysis. So, at what time(s) should such FTO search updates be performed? There are actually multiple possible approaches.

Discrete FTO Updates

A first approach is to perform one or more discrete FTO updates that resemble the initial FTO search and analysis. The timing of such discrete updates can be based on product- or technology-based milestones and/or calendar- or timeline-based milestones.

A typical product/technology milestone would be the release of a new or different version of a given product that has new, improved, or simply different features and functionality. An example would be releasing version 1.1 or 2.0 of a product that was previously cleared for its version 1.0 design only. Another typical product/technology milestone would be the occurrence of a particular pre-release design review phase. Technologies that have relatively long development cycles sometimes go through formalized design review processes with multiple distinct phases. In each phase changes to the product design might be introduced. For instance, a given initial product design might work well in prototype form but later be discovered to be too difficult to manufacture efficiently and thus might be replaced with a more easily manufactured design that was not previously searched.

An example of a calendar-based milestone would be to simply conduct a search update on a set periodic cycle, such as every year, or a single time after 18 months have passed since the original FTO search. There is no right or wrong update time period here, or even an particular appropriate number of updates. This is really a trade-off between the burden and expense of each update and the infringement risks likely raised, including the density of ongoing patenting on relevant technologies. Though recall that unpublished pending patent applications might first become available 18 months (or more) after the original FTO search.

Ongoing Monitoring

It is also possible to conduct ongoing monitoring of all patents and published applications for:

  • particular competitor(s)
  • particular technology area(s)

Ongoing monitoring can be facilitated through the use of alerts/saved criteria set up with proprietary search platforms or, alternatively, periodic (manual) searches. Such ongoing monitoring can take place in addition to or in place of other milestones or criteria for an FTO search. The main decision points with respect to ongoing monitoring are when to start and when to stop monitoring, and the scope regarding which competitor(s) and/or technology area(s) are included. Those factors are often highly influenced by the time and resource commitments required, as well as the relevance of those efforts to planned or ongoing commercial activities. It is worthwhile to periodically revisit the parameters for ongoing patent monitoring efforts, to ensure that those efforts are still relevant and appropriately focused.

Have an invention you would like to patent? Have a brand you would like to register as a trademark? Concerned about infringing someone else’s intellectual property? Is someone else infringing your IP? Need representation in an IP dispute? Austen is a patent attorney / trademark attorney who can help. These and other IP issues are his area of expertise. Contact Austen today to discuss.

Patents Q&A

When Should a Patentability Search Be Performed?

A full assessment of patentability requires identifying the closest prior art and then performing a legal analysis of the invention you want to patent in light of that prior art. Doing this meaningfully requires a patentability search. You need to conduct a patentability search at the right time to get the most value from it. An example timeline for a patentability search is shown below. This example timeline is meant to illustrate best practices for timing a patentability search in relation to filing a new patent application.

graphic of timeline for patentability search

You start with an initial idea or business case. That is the point at which there is a commitment to spend time and resources to try to come up with an invention. But it may be no more than a wish or plan. Sometime after that research & development (R&D) and product development begins. And at some point one or more inventions are conceived. That might occur at the same time as the initial idea or closely following it. Or there might be considerable R&D and development work needed before it appears that an actual invention has been conceived.

The invention is ready for patenting when it is possible to document how to make and use it. This might happen at the same time as conception. Or an invention might start as a loose collection of thoughts in the inventor’s and require extensive experimental testing before before the details can be meaningfully documented. Building a working prototype is sufficient but not required. Sometimes you might just want to test different embodiments to determine which is most viable. What matters most is that an invention must be sufficiently developed beyond a mere wish or plan to invent before a patent application can be prepared. But the applicant also has to subjectively feel ready to move forward with patenting a particular invention too.

Ideally, a patent application should be filed before any public disclosure, public use, or commercialization of the invention. This is required in many countries. Though there is a one-year grace period for patent filings in the United States after a public disclosure or sale by the inventor.

The patentability search should ideally be conducted before patent application drafting begins. This allows the results of the patentability search to be fully taken into account while preparing the application. It is often possible to write a better patent application when the closest prior art is known. Differences and improvements over the prior art can be described more thoroughly. Also, if the patentability search is unfavorable then you can avoid the expense of preparing and filing a patent application. That is one of the best reasons to perform a search.

It is possible to perform a patentability search while a patent application is being prepared. But once application drafting has begun it gets progressively harder to incorporate search results. And once a non-provisional application is filed the benefits of a patentability search drop close to zero. Though searches are still beneficial when done between the filing of a provisional patent application and the preparation of a non-provisional application.

But a particular invention must already be conceived before the patentability search is performed. If you don’t have any idea what the invention actually is, you cannot perform a meaningful patentability search. Otherwise you wouldn’t know what to search for. These searches are directly tied to the invention you want to patent after all. If you haven’t actually conceived an invention yet and just want to evaluate business opportunities (rather than patentability) then a landscape search is more appropriate.

In some circumstances, you may wish to delay a patentability search. That can help avoid wasted search effort if other inventions might take precedence in business plans. But, on the other hand, a patentability search might help you determine if an invention is ready and worthy of patenting. Applicants have wide latitude to define their inventions however they want. Sometimes you start with a broad view of an invention but a patentability search reveals that some aspects were actually already known. You might then have to do further development in order for the most promising “new” aspects to be ready for patenting. Or you might find that the patentable aspects are simply not commercially valuable enough to pursue.

You might also combine a patentability search with a freedom-to-operate (FTO) search. FTO searches assess risks of infringement for a planned product or service. The timing has to be right for both types of searches for a combined study to make sense. The parameters and legal considerations for patentability and FTO studies also differ significantly. So a combined search always involves more effort than one search individually. But sometimes there is enough overlap in the searching effort for a combined search to make sense.

Photo of Austen Zuege

Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.


Patent Searching: (Almost) Everything You Need to Know

Reproduced here are materials presented at the AIPLA CLE webinar Patent Searching: (Almost) Everything You Need to Know on September 14, 2021. The presentation slides, which include links to patent searching resources available online, are available for download below.


Rather than a tutorial or “how-to” guide in the mechanics of searching, these program materials address important considerations that inform the planning, execution, and validation of all types of patent searches, including patentability, freedom-to-operate, invalidity, landscape, and due diligence searches. Readers will learn about timing considerations, budgeting and staffing models, export controls, privileges, evidentiary considerations for invalidity/patentability challenges, metrics for evaluating the effectiveness of a search, and more. This overview will be useful for those who perform searches themselves and those who outsource their searches to others.

I. Types of Patent Searches

The purpose of a patent “landscape” search is to ascertain the overall state of patents in a particular technology area.  While “state-of-the-art” is sometimes used synonymously with “landscape” here, a distinction can be drawn between a patent landscape search limited exclusively to patents and published patent applications and a state-of-the-art search that includes patent documents as well as non-patent publications and potentially also commercially-available products.  These searches are frequently used for competitive/business intelligence purposes.  Landscape searches may be limited to particular jurisdictions in some cases.  Reports and documentation for landscape searches are often focused on only high-level bibliographic information and the like and may omit detailed discussion of the content of specific patent claims.  Landscape search reports can be very basic but also can be highly elaborate with infographics and other more elaborate visual elements aimed at an audience of businesspeople—especially higher-level executives—rather than patent attorneys. 

Landscape searches are exploratory searches performed for business-related purposes and they are not legally required. 

A patentability search identifies potential prior art against a particular invention, and is performed in order to assess the likelihood that a patent would be granted on the invention and the potential scope of allowable/patentable subject matter.  They allow more informed judgments as to whether the costs and effort of a patent application will be worthwhile.  Results of a patentability search can also be utilized by the person(s) preparing a patent application on the invention to improve the quality of the application through better awareness of the closest prior art.[1]  The patentability search, as such, is the gathering of relevant prior art for purposes of a patentability analysis, which involves legal judgments beyond mere searching effort. 

The scope of a patentability search may be based on the contents of an invention disclosure document; changes or further developments to the invention that are not contained in such a document—or are simply not explicitly identified in a meaningful way—may not be captured by the search.  Patentability searches should capture disclosures contained anywhere in a given prior art document or product, including inherent disclosures and things visible only in the drawings.  Patentability searches ideally encompass both patent documents and non-patent publications, as well as commercially available products, available anywhere in the world.  However, as a practical matter, patentability searches are usually subject to significant constraints on their scope.  Most patentability searches are budget-constrained, whether in terms of a monetary budget or a time budget (e.g., needed by tomorrow).  Moreover, some patentability searches might be limited to only a search of patent documents, or in a database that covers only certain key jurisdictions or non-patent literature (NPL) publications.

Patentability searches are exploratory searches performed to enable a legal evaluation of patentability as well as to inform business decision-making but they are not legally required by the USPTO before filing a patent application.  Sometimes a patentability search is combined with a freedom-to-operate (FTO) search. 

Due diligence searches are performed in various contexts where it is desired to verify the current ownership/assignment of given patent(s) or application(s) and to identify potential clouds on title, to establish family and other bibliographic data, and to vet corporate mergers & acquisitions (M&A) that involve patent assets and other patent licensing or acquisition opportunities (e.g., to assess scope, validity, valuation).  In the due diligence context, searching may be focused on ascertaining ancillary data for a known or limited universe of patents.  Due diligence searches may shade into other types of searches.  For instance, a freedom-to-operate search may be performed to assess infringement risks associated with a product line or technology acquisition.  Also, sometimes invalidity searches are performed during acquisitions in order to assess the strength of acquisition targets or even to proactively attack the patents to create leverage to drive down acquisition cost.  Another situation where due diligence searches can be utilized is in preparation for enforcement. 

Due diligence searches can be considered exploratory searches.  There is generally no affirmative legal duty to perform a due diligence patent search.[2] 

An FTO search, also called a “clearance” or “right-to-use” search, is used to identify patents and pending patent applications that pose potential infringement risks associated with a particular product or process.[3]  “Contract clearance” searches are a subset of FTO searches for compliance with contract provisions.  The FTO search, as such, is the gathering of relevant patents and applications for purposes of an FTO analysis, which involves legal judgments beyond mere searching effort. 

The scope of an FTO search must generally first be ascertained by performing a “feature identification” or “product decomposition” analysis to identify discrete, potentially patentable features to be searched.  FTO searches focus on the claimed subject matter, and need not address non-patent materials.  Moreover, FTO searches may be limited to only jurisdictions where the product or process will be made, used, sold, or offered for sale—bearing in mind that contributory or induced infringement risks may expand the list of relevant jurisdictions in some situations. 

In order to have a reasonable basis to rule out potential infringement risks an FTO search must be reasonably comprehensive and reliable, meaning that FTO searches should ideally not be subject to arbitrary constraints.  Though in some situations an FTO search on particular feature(s) might be deferred or foregone if there is a reasonable basis to believe those feature(s) will present relatively low risk of infringement, such as where the particular feature of the product or process in question is confidently known to have been in commercial use (identically) for more than twenty years—making any recent patents directed to such a feature likely to be invalid. 

FTO searches are defensive searches performed to enable a legal evaluation of infringement risk.  Sometimes an FTO search is combined with a patentability or due diligence search.  A potential infringer is not subject to an adverse inference for failing to affirmatively conduct an FTO search and/or seek an opinion of counsel.[4]   Though the range of options to avoid liability is much greater if you find a potentially problematic patent before it finds you. 

An invalidity search is used to identify prior art that renders one or more claims of a given patent invalid.  Invalidity searches are often used to develop an invalidity defense to an allegation of infringement and/or to help establish a good faith belief in invalidity to avoid a charge of willful infringement through an advice of counsel defense.[5]  Depending on the context, such as for a challenge at the USPTO, the word “unpatentability” may apply instead of “invalidity”, in a strict sense.  In other countries, terms like “nullity” or “opposition” might be used instead of “invalidity” or “unpatentability”.  An invalidity/unpatentability search can further be used to identify prior art against one or more claims of a pending patent application, for potential use for a third-party pre-grant submission or third-party observations made to the relevant patent office. 

Invalidity searches should seek relevant disclosures contained anywhere in prior art documents or products, including inherent disclosures and things visible only in the drawings.  Invalidity searches ideally encompass both patent documents and non-patent publications, as well as commercially available products, available anywhere in the world.  Though the status of certain activities or documents as “prior art” may vary.  Research into commercially available products may take on the character of an investigation more than an exercise in database searching.  Because invalidity searches may be performed in high-stakes situations, they are often the most involved and comprehensive searches, because the extra effort and expense is justified.  For example, it may sometimes be worthwhile to commission multiple invalidity searches in different languages. 

Invalidity searches are defensive searches performed to enable a legal defense to be developed against an actual or potential allegation of infringement. Although invalidity searches are not legally mandated per se, they are generally necessary in a practical sense in order to develop and assert an invalidity defense or affirmatively challenge validity/patentability.[6] 

II. Timelines

Searches can be informally divided into two general categories: prospective and reactive

Prospective searches include landscape, patentability, and FTO searches.  The prospective category refers to a given search being performed in advance of some key decision point or action, such as before the launch of a product (FTO search), or the preparation and filing of a patent application (patentability).  Prospective searches inform such decisions and actions and, accordingly, should be timed so that completed search results are available to be analyzed prior to any deadlines for a decision or action. 

With respect to FTO searches, in particular, searching may be performed on an ongoing or periodic basis, such as to monitor patenting activity by particular competitor(s) and/or in particular technology area(s).  Additionally, there may be a need to watch the prosecution status of certain pending patent applications, to ascertain the scope of what, if anything, is later allowed or granted.  Some patent database tools include features to help facilitate various ongoing monitoring efforts.  Furthermore, FTO searches may need to be updated at a later point in time.  For instance, changes in product configuration may arise (e.g., manufacturability concerns arise close to a schedule product release that prompt a slightly different product configuration, or a new version of a product is developed years later) and require a new search—or at least a renewed analysis of existing search results.  Additionally, because patent applications are typically published 18 months from filing, though potentially only upon grant, at the time of any given FTO search there may be relevant but unpublished patent applications pending that can only be captured by a subsequent search. 

Invalidity and due diligence searches are reactive, in the sense that they are performed after some concrete or potential infringement risk comes to light or some need for confirmation arises.  There may still be deadlines for filing an answer to a complaint before a district court, filing a patent office challenge (e.g., PGR, IPR, opposition, observation), completing an M&A deal, or the like that constrains aspects of an invalidity search timeline.  One benefit of conducting FTO studies is that early identification of potentially problematic patents can help provide a longer time period for invalidity searching. 

III. Budgeting and Staffing

In the most general sense, patent searches are about solving information-retrieval problems.  While it is always (theoretically) desirable to conduct a “perfect” search, with hypothetical 100% recall and 100% precision, in the real world all searches are subject to constraints and a “perfect” search is not possible.  Those constraints may be in the form of deadlines or budget limits.  For instance, few if any patentability searches have an unlimited budget, and most operate on the premise of making reasonable efforts within some predetermined time and budget limits.  Any given search also usually includes express or implied limits on the databases, jurisdictions, and languages in which a search is conducted. 

The project management discipline has developed something called the “iron triangle”, which can be applied to the searching context.  In its most basic form, the “iron triangle” has three components: cost, speed, and quality.  Project management says you must pick only two of the three on any given project—you cannot have all three, even though those requesting searches often want all three.[7]  But the two factors selected will generally vary depending on the type of search, with patentability searches often sacrificing quality in order to achieve cost and speed objectives and with FTO and invalidity searches accepting slower timelines and/or greater costs in order to maintain high quality, for example.  Also note that if you do not pick two of the three, someone else will pick them for you.

For any given search, the amount of effort required varies depending on the density of patenting or publication in a given technology area.  Though at the beginning of a search that density may be unknown—usually this is only something that can be estimated well if numerous searches have previously been performed on related subject matter. 

graphic showing continuums of patent/publication density and search cost/effort
Continuums of Patent/Publication Density and Searching Cost/Effort

Searches can be performed by dedicated non-attorney searchers.  Though attorneys can perform searches themselves and it may be surprising to some that attorney-conducted searches may be more cost effective in some situations because legal analysis and searching per se can be done concurrently and features of search tools can help aid the legal analysis (e.g., by informing the attorney which particular keyword(s) returned a given reference and highlighting that term in a searchable document).  Prize/award-based “crowdsourcing” is another approach, usually best suited to invalidity searches. 

When retaining a person or firm to conduct a search, another common decision point is choosing between an experienced subject-matter expert (e.g., an in-house staff person) versus a “hired gun” (e.g., a professional searcher with little or no knowledge of the specific subject matter).  Because experience has a cost this is generally a cost vs. quality tradeoff. 

Export controls and similar provisions (e.g., ITAR, sanctions, DoD tranches) may prohibit (or limit) who can perform a given search, which may prohibit outsourcing a search abroad.[8]  For conventional export controls, the Commerce Control Lists (CCLs) establish what is subject to export restrictions.  The “EAR99” CCL designation generally applies to low-tech consumer goods that do not require export license in many situations.  However, “dual-use” export controls apply to things that have both military and non-military applications, and can be esoteric.  The Wassenaar Arrangement Control Lists also provide guidance on what is currently implicated by dual-use export controls.  Reexports and retransfers are also prohibited.[9]  As an example of reexport, consider that a person from a foreign country sends technical information to a searcher in the USA; the searcher may not be able to send (reexport) the same information back to that same person—here you can think of the USA like a “fly trap” for export-controlled information.  Lastly, even if you are operating entirely within the USA, a “deemed export” involves providing controlled information to a non-Green Card foreigner (or non-protected person) located in the USA.  That is, providing information to a foreigner physically located in the USA is “deemed” to be the same as exporting that information to the foreigner’s home country. 

IV. Resources for Conducting Searches

A. Introduction

It is often said that patent searching is more an art than a science.  There is no one-size-fits-all formula for conducting effective and reliable searches.  While searching does not become “easy” simply because you wish it was easy, and there is a learning curve, it is a skill that can be learned.  Fortunately, there are many resources available on the mechanics of how to conduct searches in the patent context.[10] 

There are many patent searching tools available, most of which are computer databases accessible via the Internet, though patent offices and affiliated libraries do offer some additional on-site-only resources for patent searching.[11]  Search engine functionality varies widely, with advanced features like proximity searching, bulk export of selected data, and highlighting of keywords within search results available only with certain tools.  In general, paywalled proprietary databases tend to have bells and whistles that can be helpful and save time.  Though user licenses can be significant and searchers who perform searches only occasionally will likely find yearly license fees cost-prohibitive. 

Whatever particular tool is used it is important to familiarize oneself with the scope of coverage (which jurisdictions are covered? what time periods are full-text searchable?) and the database’s search syntax, which refers to the particular operators used to command the search engine to run queries in particular ways.  While basic Boolean operators like “AND” and “OR” tend to be fairly universal, some tools require those operators to be in all caps.  More advanced operators like proximity commands or wildcard characters can be very different from one tool to the next.  Search syntax matters because a given search string or query inputted verbatim into different database tools may be parsed quite differently. 

B. Principal Database Searching Methods

While it is still possible to search for information by visiting a library and locating relevant physical publications, most patent-related searching today is performed using computer databases, most of which are now accessible via the Internet.  Computer databases useful for patent searches can be queried in a number of different ways that are ultimately a function of both the database’s search engine and metadata structure and content. 

Keyword searching, which is generally synonymous with Boolean searching, involves inputting keywords and Boolean operators (“AND”, “OR”, etc.) into a keyword string or query that the database’s search engine parses against its contents.  Database search engines have vastly different capabilities.  For instance, proximity operators are available with some databases that can be used to greatly increase the precision of keyword-based queries.  Moreover, some databases are only full-text searchable back to a particular historical date.  But be aware that not all databases or search engines are perfect, even the most full-featured tools.  A database populated by text obtained through optical character recognition (OCR) may contain errors that frustrate efforts to use the database’s search engine.  Databases that utilize machine translations of foreign patent documents for search queries may produce unreliable or unexpected machine translations in some instances.  Also, and perhaps less widely known, is that database providers may parse keyword strings in ways that deviate from what a searcher has inputted in given query.  For instance, in order to manage server computer hardware loads, to “enhance” searches, or for another reason, some search engines will include automatic thesaurus and/or pluralization functions or will parse defined phrases with spaces in between characters or as proximity searches (without the user inputting proximity operators).  Such features may increase recall but at the same time may decrease precision.  Conversely, some search engines may limit proximity searches to individual paragraphs, omitting from search results the presents of terms that are as proximate as specified but in two different paragraphs, which may reduce recall. Thesaurus functions can be helpful but cannot be relied upon exclusively.  Not only are the thesaurus lists generally hidden within a “black box” of the database software, but they often are inadequate to capture variations in technical terms used in the patent context.  For instance, an automatic thesaurus is unlikely to recognize that while “shopping cart” is a term used commonly in the USA, in Great Britain and Australia the term “shopping trolley” is used instead, or be able to ascertain whether “backhoe” and “excavator” are synonyms within the context of a given patent search.  Translations can also be a factor here.  For that matter, patentees can act as their own lexicographer.  So, a search for automatic license/number plate recognition (ALPR/ANPR) tools using conventional terminology may not locate a patent that describes such a tool as a “parkulator” (a completely invented word).[12] 

Classification searching involves reviewing patent documents according to subject-matter classifications made by patent offices.  Historically, before the advent of computerized databases, searching hard copies of patent documents by classification (stored in “shoes” at the USPTO) was the only way to search patents.  Today, there are a number of different classification systems currently in use, as well as ones that are no longer in use but can still be utilized in some situations.  The main classification systems currently in use are the International Patent Classification (IPC) system, the Cooperative Patent Classification (CPC) system, the Japanese File Index/Facet (FI) and File Forming Term (F-term) systems, and the Locarno system for design patents (and industrial designs).  The main discontinued classifications that may still have some value are the U.S. Patent Classification (USPC) system and the European Patent Classification (EPC) system, both of which were retired by the end of 2014.  While patent offices have made efforts to re-classify old patent documents under the current classification systems, the nature of differences between the old and new classification systems means that there is at most a statistical correspondence between the two that varies for different subject matter areas. 

In general, patent classification systems establish a taxonomy that includes multiple levels of detail, with highest-level classes and then multiple sub-classes within them (plus main groups/subgroups for the IPC).  Manuals or guides are available explaining these taxonomies, including descriptions of the subject matter that each class/subclass is intended to cover.  Classifications are assigned to individual patent documents by examiners, generally at an initial or pre-examination stage.  Because the process of classification necessarily involves certain judgments, classifications can be prone to human error.  Moreover, even in the best of circumstances, classifications are never perfect.  For instance, at any given point in time classification systems may not recognize certain emerging technology areas in the sense that there may not be specific sub-classes in which to categorize such emerging technologies.  Also, there may be subtle disclosures, such as things shown only in figures and/or left up to implication in the text, that may not be completely captured by a given patent office’s classifications.   And yet, classifications can be a useful tool for patent searching.  It is possible to combine classifications with particular keywords/terms as part of Boolean searches, which can be a powerful strategy to increase the precision of queries.

Forward and backward searching refers to searching references that are cited in the “references cited” section of a given relevant patent (backward searching) or searching for later patents in which the “references cited” section cites back to a given relevant patent (forward searching).  The essence of forward and backward searching is that you begin with one or more patent documents that you have already determined to contain relevant subject matter and then you piggyback on prior searches that others have performed in relation to other patents, leveraging the past efforts of others to compile groupings of technologically-related references.  In other words, forward and backward searching treats citations within and back to a given relevant patent as a kind of quasi-classification system. But forward and backward searching can never be the initial starting point for a search, because you must begin with at least one relevant patent—ideally the most relevant patent(s) you could find through other avenues.  Yet forward and backward searching can sometimes be the most effective method for increasing search recall. The same principles can be applied to citations and bibliographies in non-patent literature.

Other available patent searching tools utilize natural language searching, semantic searching, machine learning, artificial intelligence (AI), or the like.  Typically, such search tools utilize some type of proprietary algorithms to parse and execute search queries.  With natural language, semantic, or AI searching, the general idea is often that a searcher inputs words in a narrative format—unlike formal Boolean search syntax—and the tool applies its algorithms to convert those inputs into one or more queries that are run against the database to produce a result set.  Of note is that the use of proprietary algorithms mean that the search tool runs these searches through what can be called a “black box”—the searcher typically has no idea what happens inside that black box and thus no real sense of what might be omitted or excluded from the result set.  Some evidence from the legal research context suggests that experienced attorneys do not trust “black box” search algorithms.[13]  There are some tools, potentially most applicable to design patent searching (or trade dress searches), in which a searcher uploads an image file and the search tool utilizes image matching software to try to locate documents containing similar images.  As of today, these patent searching tools are still “bleeding edge” technologies and there is generally a lack of independent and peer-reviewed studies to validate the effectiveness of AI (etc.) them.  Vendors frequently make claims about studies they have done themselves, though it is difficult to place any trust in such studies used for marketing purposes when often there is no disclosure of the methodology employed and vendors have strong incentives to succumb to self-interest bias.  Much of the available literature on the subject can be characterized as marketing “advertorials”.  And for that matter, because AI-powered tools almost always rely on proprietary “black box” algorithms there is no way to know how a study involving one black box relates to another black box—or even if a study of a given search tool in the past still applies to that search tool, given that changes to that proprietary tool may occur within the black box without any way for a user or investigator to know.  These concerns echo the reasons experienced attorneys do not trust black box legal research tools or with concerns over law enforcement usage of AI-powered facial-recognition tools or the like[14]—control is being surrendered over aspects of search queries to algorithms premised on undisclosed assumptions that may be important to outcomes.  Perhaps as AI-powered patent searching tools become more sophisticated they will play a larger role.  But as of today, a good rule of thumb is to rely principally on human-guided searches and utilize AI-type search tools only in a secondary sense, such as for initial “quick-start” or “drunk walk” search orientation efforts before running substantive queries, last-step search validation or auditing, or supplemental, almost “hail Mary pass” efforts to perhaps get lucky and find additional art otherwise missed through other avenues. 

C. INID and Kind Codes

“INID” is an acronym for “Internationally agreed Numbers for the Identification of (bibliographic) Data” on patents.[15]  Also referred to informally as “field codes”, these codes embody a system for the international harmonization of bibliographic data (or metadata) appearing on published patent documents, such as for the title (54), assignee name(s) (73), filing date (22), issue/grant date (45), etc. 

INID CodeData Field Content
(10)Publication/Patent Number
(22)Filing Date
(43)Application Publication Date
(45)Grant/Issue Date
(86)PCT Filing Details
Table of Selected INID “Field” Codes

These INID/field codes can be tremendously useful when fetching individual patents in another language.  For example, either by referring to a table that identifies INID code numbers and the associate data content description, or simply referring to a sample patent in a known language, the location of similar data on a foreign-language patent document can be located.  While machine translations of patent documents are now frequently available, machine translations of very old patent documents are not always available.  And many machine translation tools may be unable to reliably parse PDFs of old patent documents, though it may be possible to perform limited machine translations of just particular text—such as within a given INID field—to ascertain some basic information about a given patent document.  

Comparison of INID “Field” Codes Between Patents in Different Languages
Camera-Based Partial Machine Translation of Selected Patent INID “Field” Contents

“Kind codes” identify type of patent and generally appear as a letter or letter and number (e.g., “A1” or “B2”) immediately after the patent or publication number.[16]  The USPTO only began printing kind codes on U.S. patent documents on January 2, 2001, so older U.S. patents lack a kind code.  Some countries have different types of patents—like utility models—that do not exist in the USA.  And systems for assigning numbers to patents has, historically, not been particularly harmonized internationally. 

Perhaps most confusing to U.S. practitioners is the Japanese patent numbering system, which in the past has assigned the same numbers to different patents differentiated only by the kind code. 

Another potentially confusing practice involves the treatment of old U.S. patents that were issued without any kind code on their face to which the “A” kind code (without a numerical digit) is retroactively applied.  This is potentially confusing because WIPO kind codes “A1”, “A2”, and “A9” are currently used by the USPTO to designate published patent applications.  In other words, the old granted patent “A” designation retroactively applied in searching databases can easily be confused with the new “A1”, “A2”, and “A9” designations that apply only to published applications and never to granted patents. 

V. Metrics for Evaluating Searches

The key metrics for evaluating information retrieval effectiveness in the patent context (or other library science contexts) are “precision” and “recall”.  Recall is the proportion (%) of all relevant documents retrieved in a given search query or overall search; recall is hypothetically expressed as:

Recall = relevant documents actually retrieved divided by universe of all relevant documents

Precision is the proportion (%) of relevant documents versus irrelevant documents retrieved in a given search query or overall search; precision is hypothetically expressed as:

Precision = relevant documents retrieved divided by total relevant & irrelevant documents retreived

Put yet another way, perhaps more informally, “recall” measures how completely relevant materials have been located while “precision” measures how much unwanted or useless material has been captured.  Library science has shown that recall and precision are tradeoffs with any given search query.[17]  That is, increasing recall generally decreases precision and vice-versa

In the patent searching context, 100% recall is always desired but 100% recall is only a theoretical objective.  There is no way to know, definitively, the universe of all relevant materials against which to compare a given query or overall search.  After all, if you knew at the outset what all the relevant materials were, why would you bother conducting a search merely to confirm what you already know?  And yet, if further searching returns additional relevant results than you can retroactively determine that a prior query or set of queries had less than 100% recall.  The rub is that this aspect of ascertaining 100% recall is like the impossibility of “proving a negative”: no matter how much you have searched, you can never know for certain whether or not there is at least one additional relevant reference that you simply have not yet located.  At best, certain protocols can be employed as proxies for 100% recall (e.g., searching X number of databases for Y number of hours, finding no more relevant results after a certain number of queries or period of time, etc.) but such proxies necessarily involve certain assumptions that can always be questioned. 

When is search complete? graphic, with learning curve-like graph

Practically speaking, precision is about efficiency and reliability.  Search results that include irrelevant materials can raise questions about the reliability of the search—did the searcher not understand the specific information being sought?—and can also waste time—both in terms of requiring more efforts by the searcher but also impeding later work by anyone else utilizing imprecise, cluttered search results for a legal analysis or to make business decisions. 

Some patent searching databases assign “relevancy” scores to individual results in a given query.  Such “relevancy” scores are generally determined by proprietary algorithms baked into the database’s software.  Whether the judgments embodied in those algorithms suit a searcher’s purpose is hard to know.  Most vendors do not make public the algorithms or weighting used to assign relevancy scores.  Searchers can anecdotally attest to performing searches where the “silver bullet” prior art was assigned a low relevancy score by the database tool.  Database “relevancy” scores are not meaningful as metrics for assessing search quality.  Though they might still be useful in (theoretically) presenting voluminous query results in an order that is more helpful for review. 

VI. Evidentiary Burdens, Privileges, and Disclosure Duties

A. Evidentiary Issues for NPL References and Public Use/On-Sale Evidence

District court proceedings where invalidity is alleged follow the Federal Rules of Evidence (FRE).[18]  PTAB trials at the USPTO (PGRs, IPRs, Derivations) also generally follow the FRE.[19]  Under the FRE, a document introduced as “prior art” must satisfy rules requiring authentication and prohibiting hearsay (unless an exception applies).[20]  These evidentiary burdens are not a concern for U.S. patents and published patent applications, which as “public records” are self-authenticating (FRE 902) and fall in a hearsay exception (FRE 803(8)) to qualify them as prior art.  In practical terms, authentication/hearsay objections to foreign patents and published patent applications are unlikely—and a party bringing such objections is just going to annoy the judge.  Evidentiary issues surrounding domestic and foreign patents should really only arise in rare if not unheard-of situations where forgeries are being proffered.  But evidentiary issues for NPL references, on-sale activities, and the like cannot be taken for granted.[21]  For instance, the Federal Circuit has held that “corroboration is required of any witness whose testimony alone is asserted to invalidate a patent.”[22] 

However, during ordinary examination and reexamination lower evidentiary standards apply to NPL references and compliance with the FRE (or similar PTAB trial procedures) is unnecessary.[23]

B. Qualifying a Non-Patent Literature (NPL) Reference as “Prior Art”

In order to qualify as “prior art”, an NPL reference must be established as a “printed publication” that was sufficiently generally “publicly accessible” before the critical date—and that must be done in accordance with the hearsay and authentication requirements discussed above for district court litigation and PTAB trials.  “‘[P]ublic accessibility’ has been called the touchstone in determining whether a reference constitutes a ‘printed publication[.]’”[24]  “A reference will be considered publicly accessible if it was disseminated or otherwise made available to the extent that persons interested and ordinarily skilled in the subject matter or art exercising reasonable diligence[] can locate it.”[25]  “Whether a reference is publicly accessible is determined on a case-by-case basis based on the ‘facts and circumstances surrounding the reference’s disclosure to members of the public.’”[26]  Limited distribution, even to those skilled in the art, may not amount to “publication” unless the material is otherwise so situated that “anyone who chooses may avail himself of the information it contains.”[27]  While evidence of “indexing” can establish public accessibility, it is merely one among many ways to establish “printed publication” status.[28]

In the invalidity context, it cannot be assumed that a copyright date, printing date, Internet server upload date, or the like appearing on the face of the NPL reference will necessarily satisfy public availability evidentiary requirement.  Courts and the PTAB have rejected such arguments in numerous cases.[29]  But clear indications on or within an NPL reference evincing publication by an established publisher with traditional hallmarks of publication (ISBN, etc.) might be sufficient.  Courts and the PTAB have occasionally found such evidence sufficient, particularly when dealing with very conventional publications like a (hard copy) book from a well-known publisher or an industry standard published by a well-known standards-setting organization.[30]  Commonly, the publication of NPL materials is substantiated by testimony from a librarian who cataloged or indexed a book or magazine as of a particular date.  In those situations, merely finding a particular disclosure is not enough to qualify the NPL reference as “prior art”—it may also be necessary to locate a witness to corroborate public accessibility. 

Materials from Internet web sites constitute an important category of NPL references where hearsay concerns can be significant.  Once again, the mere appearance of a date on the face of a web page (or in the URL, etc.) will not ordinarily be sufficient to establish the web page as a printed publication that qualifies as “prior art” before a critical date.  It is possible to offer witness testimony to establish web page publication, just as with books, magazines, and the like.  But one unique avenue for satisfying evidentiary burdens to qualify a web page as prior art is to utilize archival records from the Internet Archive’s “Wayback Machine” ( or its equivalent.[31] 

Other ephemeral or temporarily displayed materials, such as posters, videos, or presentation slides temporarily displayed at trade shows or conferences, raise other unique issues regarding their status as printed publications that qualify as “prior art”.[32]  But they may qualify as prior art under various circumstances.

Also remember that standards of proof differ depending on where a validity or unpatentability challenge is lodged.  A preponderance of the evidence standard is applied at the USPTO whereas a clear and convincing evidence standard is applied in district courts.  These different standards of proof can make a difference in whether or not available evidence establishes something as “prior art”.  Some reported decisions are less than explicit about the standard of proof being applied, which may help make sense of decisions that otherwise might seem inconsistent. 

C. Privileges and Their Limits

The attorney-client privilege and work-product protections may shield certain materials from discovery.  Yet materials generated in connection with searches are not always privileged. 

Attorney-client privilege only applies to communications actually sent, and only when seeking or providing legal advice.[33]  Such communications must involve an attorney or someone acting under the supervision and control of an attorney; and just because a communication involves an attorney does not automatically mean it is privileged.  Privilege law varies across district courts and circuits but some courts have held that the acts of counsel, the general topics of discussion, and the ultimate legal conclusions are not privileged.  Moreover, communications involving in-house counsel are often scrutinized more closely and may be subject to a rebuttable presumption that they contain business rather than legal advice.[34]  In general, anything that would have to be disclosed on a privilege log in litigation is not privileged.[35]  For instance, a privilege log may need to identify patents by number, and documents found during patent infringement/prior art searches or reviewed by an expert witness might need to be identified or disclosed.[36]

Work product protection can preclude discovery of documents and tangible things that are “prepared in anticipation of litigation or for trial” by or for another party or its representative (including the other party’s attorney, consultant, or agent).[37]  Work product protections can apply to the work product of non-attorneys but will not apply where business considerations predominate (regardless of the involvement of any attorney(s)).[38]  Also, work product protection is not absolute, and can be overcome if the materials are otherwise discoverable and the party seeking discovery shows that it has substantial need for the materials to prepare its case and cannot, without undue hardship, obtain their substantial equivalent by other means.[39] 

D. Duty of Disclosure

The duty of disclosure applicable to pending U.S. patent applications may necessitate some additional steps when relevant prior art is located in a search.  “Each individual associated with the filing and prosecution of a patent application has a duty of candor and good faith in dealing with the [USPTO], which includes a duty to disclose  . . . all information known to that individual to be material to patentability . . . .”[40]  Deliberately withholding prior art material to patentability can render any resulting patent unenforceable.[41]  Anyone substantively involved[42] with pending U.S. patent application(s) who receives search results on related subject matter should consider the need to submit search results on an information disclosure statement (IDS). 

VII. Considerations for USPTO Post Grant Proceedings

Strategic and legal considerations regarding the type of post-grant challenge that might be leveled against a given patent will vary depending upon the available prior art.  For that reason, it is usually desirable to locate prior art, or at least most of it, before deciding which type of post-grant proceeding will be sought.  For example, certain types of post-grant proceedings can only be based on patents and printed publications.  Moreover, the thresholds for institution of different types of proceedings vary;[43] though one constant is that all USPTO post-grant proceedings are based on a preponderance of the evidence standard for patentability while district court actions are based on the higher clear and convincing evidence standard for invalidity.  Lastly, IPR institutions are on an all-or-nothing basis.[44] 

PTAB trials involve estoppel that bars any further challenge based on any ground the petitioner “raised or reasonably could have raised” in a prior proceeding.[45]  This amounts to a “use it or lose it” (or “cite it or forgetaboutit”) opportunity to present prior art in a PTAB trial petition for institution, and requires that essentially all prior art searching be completed before the petition is filed—and therefore, practically speaking, before a petition can be prepared by legal counsel.  The PTAB and some district courts have interpreted and applied the “raised or reasonably could have raised” standard by asking whether a skilled searcher conducting a diligent search reasonably could have been expected to discover the prior art reference in question.[46]  The PTAB has applied this standard in a rather strict and formalistic way, showing no sympathy if locating a patent document would have required “brute force” manual review of tens or hundreds of thousands of patents not in any apparently relevant class/subclass.[47]  Courts have also considered whether particular prior art, such as a physical product that is not a “printed publication” but was potentialyl was on sale or in public use, reasonably could have been raised in a PTAB trial.[48] 

On the other hand, estoppel does not arise from ex parte reexamination.  Though collateral estoppel (issue preclusion) from prior litigation can still apply to reexams.[49]  Additionally, it is more difficult to sustain the unchanging clear and convincing evidence burden for subsequent invalidity challenges in district court when the USPTO already considered the same art.[50] 

VIII. Considerations for Design Patents

For design searching, “brute force” manual review of all designs in relevant classifications is recommended.  A major reason is that design patents have so little text that keyword searching is frequently unreliable.  There is so little text that explanatory statements that normally appear in utility patents to provide an enabling disclosure for functional features is absent in design patents focused on ornamentation.  And what little text there is in design patents might use words that are not especially helpful or reliable for purposes of a keyword search.  Though initial keyword searching can still be helpful when seeking to identify relevant Locarno classifications.  Another tip is to be sure to check for alternate embodiments that are not depicted in a representative figure on the front page of the design patent (or shown in representative thumbnail views by search tool databases).  Another point to consider for design patents is that some subject matter areas may have relatively few prior art design patents, even in areas where commercial products have been sold and publicly used for decades.  In such situations it may be necessary to investigate non-patent prior art in the form of evidence of on-sale activities, etc.  Such investigations may call for a substantially different approach and timeline.  Actually, such investigations may require considerable effort to locate and authenticate suitable evidence including witnesses/declarants

Another challenge with design patent searching is that the Federal Circuit looks to the perspective of the ordinary designer (rather than the ordinary observer) for obviousness analyses and applies a two-part Durling test for obviousness.[51] 

Somewhat unique to design patents is the opportunity to present prior art for a three-way comparison between images of the asserted patent, the prior art, and the accused product in “close” cases.[52]  The burden is on the accused infringer to bring forward evidence of the closest prior art for a three-way comparison.[53] 

Photo of Austen Zuege

Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.

Book available from the ABA. Includes extended treatment of patent searching techniques.


[1] See Paul C. Haughey, “Patentability Searches – Bust or Save In-house Counsel Budgets?” Lexology (April 9, 2020).

[2] E.g., Digeo, Inc. v. Audible, Inc., 505 F.3d 1362, 1369-70 (Fed. Cir. 2007) (case not exceptional [frivolous] because defendant did not establish plaintiff knew or should have known it lacked legal title due to alleged forgeries); Q-Pharma, Inc. v. Andrew Jergens Co., 360 F.3d 1295, 1303 (Fed. Cir. 2004) (reasonable belief in presumption of validity made suit nonfrivolous under Rule 11). 

[3] See, generally, Patent Freedom to Operate Searches, Opinions, Techniques, and Studies (Austen Zuege, ed., ABA 2017).

[4] 35 U.S.C. § 298; see also Knorr-Bremse Systeme Fuer Nutzfahrzeuge GmbH v. Dana Corp., 383 F.3d 1337, 1345-46 (Fed. Cir. 2004) (en banc) abrogated by In re Seagate Tech., LLC, 497 F.3d 1360, 1371 (Fed. Cir. 2007) (en banc); Seagate, 497 F.3d at 1371 abrogated on other grounds by Halo Elecs., Inc. v. Pulse Elecs., Inc., 979 U.S. ___, 136 S. Ct. 1923 (2016).

[5] See, e.g., The Sedona Conference, “Commentary on Patent Litigation Best Practices: Willful Infringement Chapter” (July 2020 Public Comment Version).

[6] There may be rare situations in which relevant prior art is already known without conducting an invalidity search, though even then a search to locate additional prior art may have value. 

[7] E.g., Mike Morrison, “The Project Management Triangle – Time, Quality, Cost – You Can Have Any Two,” (March 23, 2017).

[8] See 15 C.F.R. Part 730; 22 C.F.R. Part 120; 31 C.F.R. Part 501; Bureau of Industry and Security, “Export Administration Regulations (EAR)”; U.S. Department of State, “Understand the ITAR and Export Controls”; Krauland et al., “State Department Publishes Long-awaited ITAR Rule on Encryption and Other Excluded Activities” Lexology (Dec. 24, 2019); U.S. Dept. of the Treasury, “Sanctions Programs and Country Information”; U.S. Dept. of the Treasury, “Consolidated Sanctions List Data Files”; U.S. Dept. of Defense, “DOD Releases List of Additional Companies, In Accordance with Section 1237 of FY99 NDAA” (Jan. 14, 2021).

[9]  15 C.F.R. § 734.14; 22 C.F.R. §§ 120.19 and 120.51.

[10] E.g., Patent Freedom to Operate Searches, Opinions, Techniques, and Studies, supra; Stephen P. Harter, Online Information Retrieval: Concepts, Principles, and Techniques (1986); David Hunt et al., Patent Searching: Tools & Techniques (2007); WIPO, “Guidelines for Preparing Patent Landscape Reports” (2015).

[11] See WIPO, “INSPIRE” at <>.

[12] U.S. Pat. No. 6,243,029 B1.

[13] Brian Sheppard, “Does Machine-Learning-Powered Software Make Good Research Decisions? Lawyers Can’t Know for Sure,” ABA Journal New Normal (Nov. 22, 2016).

[14] See, e.g., Grother et al., National Institute of Standards and Technology (NIST), “Face Recognition Vendor Test (FRVT) – Part 3: Demographic Effects,” NISTIR 8280 (Dec. 2019); “What is Math Washing?,” (last visited Jan. 29, 2021); Lyle Moran, “Pretrial Risk-Assessment Tools Should Only Be Used if They’re Transparent and Unbiased, Warns ABA House” (Feb. 14, 2022).  Note also Jacques Lacan’s concept of “university discourse.”  See, e.g., Jeffrey & Dolar, “The Sting of Knowledge,” The Point Magazine, Issue 16 (April 23, 2018); Bruce Fink, The Lacanian Subject (1995), pp. 132-33.

[15] WIPO, “Standard ST.9: Recommendation Concerning Bibliographic Data on and Relating to Patents and SPCS” (June 2013); WIPO, “Standard ST.80: Recommendation Concerning Bibliographic Data Relating to Industrial Designs” (February 2004); MPEP § 901.05(b)

[16] WIPO, “Standard ST.16: Recommended Standard Code for the Identification of Different Kinds of Patent Documents” (Oct. 2016); MPEP § 901.04(a); USPTO, “‘Kind Codes’ Included on the USPTO Patent Documents” (Sept. 18, 2013).

[17] David M.W. Powers, “Evaluation: From Precision, Recall and F-Measure to ROC, Informedness, Markedness & Correlation,” 2(1) J. Machine Learning Techs. 37, 37-63 (2011).

[18] See also, generally, Evidence in Patent Cases (Dorsney, ed., Bloomberg Law 2018).

[19] 37 CFR § 42.62; see also USPTO, “Hearsay and Authentication” (Dec. 6, 2018).

[20] Article VIII – FRE 801-807: Hearsay; Article IX – FRE 901-903: Authentication; but see, e.g., 37 CFR § 42.61 (admissibility in PTAB trials). 

[21] Cf. Wi-LAN Inc. v. Sharp Elecs. Corp., 992 F.3d 1366 (Fed. Cir. 2021) (proffered evidence of infringement inadmissible at summary judgment for lack of suitable authentication; 3d Circuit law applied).

[22] Texas Digital Sys., Inc. v. Telegenix, Inc., 308 F.3d 1193, 1217 (Fed. Cir. 2002); see also Juicy Whip, Inc. v. Orange Bang, Inc., 292 F.3d 728, 741-42 (Fed. Cir. 2002) (“rule of reason” and factors for assessing sufficiency of corroboration).

[23] E.g., MPEP § 2128 (date on a document can establish its publication for examination purposes unless applicant challenges it); Ex parte Grillo-López, Appeal No. 2018-006082 at *2-3 (PTAB, Jan. 31, 2020) (precedential) (lower examination standards vs. higher IPR standards to establish publication).

[24] In re Hall, 781 F.2d 897, 899 (Fed. Cir. 1986).

[25] Medtronic, Inc. v. Barry, 891 F.3d 1368, 1380 (Fed. Cir. 2018).

[26] In re Lister, 583 F.3d 1307, 1311 (Fed. Cir. 2009) (quoting In re Klopfenstein, 380 F.3d 1345, 1350 (Fed. Cir. 2004)); see also Blue Calypso, LLC v. Groupon, Inc., 815 F.3d 1331, 1348 (Fed. Cir. 2016) (“Whether a reference qualifies as a printed publication is a legal conclusion based on underlying factual determinations.”).

[27] In re Bayer, 568 F.2d 1357, 1360, 1362 (CCPA 1978).

[28] E.g., In re Lister, 583 F.3d at 1312 (“neither cataloging nor indexing is a necessary condition for a reference to be publicly accessible.”).

[29] E.g., Samsung Electronics Co., Ltd. v. InfoBridge Pte. Ltd., IPR2017-00099,-00100, Paper 43 (PTAB, Nov. 13, 2020) (remanded from Samsung Elecs. Co., Ltd. v. InfoBridge Pte. Ltd., 929 F.3d 1363, 1372 (Fed. Cir. 2019)); Acceleration Bay, LLC v. Activision Blizzard Inc., 908 F.3d 765, 773 (Fed. Cir. 2018); Blue Calypso, LLC v. Groupon, Inc., 815 F.3d 1331, 1348-49 (Fed. Cir. 2016); Open Text SA v. Box, Inc., No. 3:13-cv-04910, 2015 WL 4940798 at *7 (N.D. Cal. Aug. 19, 2015); CNET Networks, Inc. v. Etilize, Inc., 584 F. Supp. 2d 1260, 1274 (N.D. Cal. 2008).

[30] E.g., VidStream LLC v. Twitter, Inc., 981 F.3d 1060, 1066-67 (Fed. Cir. 2020); Hulu, LLC v. Sound View Innovations, LLC, Case IPR2018-01039, Paper 29 at *17-21 (PTAB, Dec. 20, 2019) (precedential); Ericsson Inc. v. Intellectual Ventures I LLC, IPR2014-00527, Paper 41 (PTAB, May 18, 2015); Kyocera Wireless Corp. v. Int’l Trade Comm’n, 545 F.3d 1340, 1351 (Fed. Cir. 2008).

[31] Valve Corp. v. Ironburg Inventions Ltd., Nos. 2020-1315, 2020-1316, and 2020-1379, Slip Op. at *16  (Fed. Cir., Aug. 17, 2021); James L. Quarles III and Richard A. Crudo, “[Way]Back to the Future: Using the Wayback Machine in Patent Litigation,” ABA Landslide, Vol. 6, No. 3 (Jan./Feb. 2014); see also Internet Archive, “Frequently Asked Questions”; Archive.Today at <>.

[32] See, e.g., Medtronic, 891 F.3d at 1379-83; Initiative for Medics., Access & Knowledge (I-MAK), Inc. v. Gilead Pharmasset LLC, IPR2018-00123, Paper 7 at *8-11 (PTAB, June 13, 2018); In re Klopfenstein, 380 F.3d at 1347-50; Ecolochem, Inc. v. S. Cal. Edison Co., 227 F.3d 1361, 1369-70 (Fed. Cir. 2000).

[33] See, generally, Jackie Unger, “Maintaining the Privilege: A Refresher on Important Aspects of the Attorney-Client Privilege,” Business Law Today (Oct. 2013).

[34] E.g., Lindley v. Life Inv’rs Ins. Co. of Am., 267 F.R.D. 382, 389 (N.D. Okla. 2010), aff’d in part as modified, No. 08-CV-0379-CVE-PJC, 2010 WL 1741407 (N.D. Okla., Apr. 28, 2010).

[35] See F.R. Civ. P. 26(b)(5); see also, e.g., Travis S. Hunter and Sara M. Metzler, “Is It Privileged? A Young Lawyer’s Guide to Preparing a Privilege Log in Commercial Litigation,” ABA Practice Points (June 29, 2018); Michael Downey and Paige Tungate, “Practical Advice on Privilege Logs,” Law Practice Today (Sept. 14, 2018). 

[36] E.g., Baxter Int’l, Inc. v. Becton, Dickinson and Co., No. 17-C-7576 (N.D. Ill, July 26, 2019); BASF Catalysts LLC v Aristo, Inc., No. 2:07-cv-222, 2009 WL 187808 (N.D. Ind., Jan. 23, 2009); Adobe Inc. v. RAH Color Techs. LLC, Nos. IPR2019-00627, -00628, -00629, -00646, Paper 59 (PTAB, Dec. 12, 2019).

[37] F.R. Civ. P. 26(b)(3)(A)

[38] E.g., Sioux Steel Co. v. Prairie Land Millwright Servs., Inc., No. 1:16-cv-02212 (N.D. Ill., May 19, 2021) (factual information in technical drawings related to attempts to design around patent discoverable, but counsel’s mental impressions and opinions about those efforts and legal advice sought or received not discoverable); In re Google Inc., 462 F. App’x 975, 976-79 (Fed. Cir. 2012) (nonprecedential) (email captioned “Attorney Work Product” expressing need for license was a technical/business investigation not protected work product, nor attorney-client privileged); Takeda Chem. Inds., Ltd. v. Alphapharm Pty., Ltd., No. 04-cv-1966, 2005 WL 1678001 (S.D.N.Y., July 19, 2005) (routine patent searches in ordinary course of business, irrespective of litigation, not protected work product).

[39] F.R. Civ. P. 26(b)(3)(A)

[40] 37 C.F.R. § 1.56; see also MPEP Chapter 2000.

[41] Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011 (en banc); see also, e.g., GS Cleantech Corp. v. Adkins Energy LLC, 951 F.3d 1310, 1328-32 (Fed. Cir. 2020).

[42] See Avid Identification Sys. Inc. v. Crystal Import Corp. SA, 603 F.3d 967, 974 (Fed. Cir. 2010).

[43] See USPTO, “Major Differences Between IPR, PGR, and CBM”.

[44] SAS Institute, Inc. v. Iancu, 584 U.S. ___, 138 S.Ct. 1348 (2018).

[45] 35 U.S.C. §§ 315(e) and 325(e); see also Wi-LAN Inc. v. LG Elecs. Inc., 421 F. Supp. 3d 911, 923-24 (S.D. Cal. 2019).

[46] Wasica Finance GmbH v. Schrader Int’l, 432 F. Supp. 3d 448, 453 (D. Del. 2020); IBM Corp. v. Intellectual Ventures II LLC, No. IPR2014-01465, Paper 32 at 5 (PTAB, Nov. 6, 2015).

[47] Valve Corp. v. Ironburg Inventions Ltd., IPR2017-00137, Paper 43 (PTAB, Jan. 25, 2018).

[48] E.g., The California Inst. of Tech. v. Broadcom Ltd., No. 2:16-cv-03714, Slip. Op. at *7-10 (C.D. Cal., Aug. 9, 2019); Wasica, 432 F. Supp. 3d at 452-55; Star Envirotech, Inc. v. Redline Detection, LLC, No. 8:12-cv-01861, 2015 WL 4744394, at *4 (C.D. Cal. Jan. 29, 2015).

[49] In re Freeman, 30 F.3d 1459 (Fed. Cir. 1994).

[50] Am. Hoist & Derrick Co. v. Sowa & Sons, Inc., 725 F.2d 1350, 1360 (Fed. Cir. 1984); accord Microsoft Corp. v. i4i Ltd. P’ship, 564 U.S. 91, 110 (2011); see also Ingersoll-Rand Co. v. Brunner & Lay, Inc., 474 F.2d 491, 496 (5th Cir. 1973).

[51] Campbell Soup Co. v. Gamon Plus, Inc., 939 F.3d 1335, 1340-41 (Fed. Cir. 2019); High Point Design LLC v. Buyers Direct, Inc., 730 F.3d 1301, 1313 (Fed. Cir. 2013); Durling v. Spectrum Furniture Co., 101 F.3d 100, 103 (Fed. Cir. 1996); contrast KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 415-18 (2007).

[52] Egyptian Goddess, Inc. v. Swisa, Inc., 543 F.3d 665, 678 (Fed. Cir. 2008) (en banc); see also, e.g., Wallace v. Ideavillage Prods. Corp., No. 2015-107, 2016 WL 850860 (Fed. Cir., March 3, 2016) (nonprecedential).

[53] Egyptian Goddess, 543 F.3d at 678.