Patents Q&A

What Are Common Patent Drafting Mistakes?

Preparing new patent applications can be complicated. Patent applications in the U.S. and most other countries undergo pre-grant examination. So a patent application must be sufficient to establish patentability to the satisfaction of a patent examiner. And if the goal is to create enforceable exclusive legal rights in an invention, and it usually is, then there are many legal considerations that impact coverage and validity. In sum, while there are challenges to obtaining any patent at all, not all granted patents are equal.

What follows is a discussion of some of the most common mistakes when drafting a utility patent application. These are the sorts of mistakes frequently made by inventors preparing and filing an application themselves (pro se) without the aid of a patent attorney. These issues can also arise when applications prepared in another jurisdiction enters the USA and there are differences in the law and practices in the two jurisdictions.

A discussion of common mistakes in design patent applications is available elsewhere.

Focusing on the Old Rather than the New

One common mistake, especially with applications self-prepared by inventors, is to focus on the prior art and what is old and already known rather than on the new invention. Put another way, the mistake is to devote excessive effort to describing what the invention is not rather than what it is. While it is permitted to discuss the background of the invention, and sometimes this is helpful to highlight what is new and different about the invention, this provides little benefit when it takes up too large a proportion of an application.

As an example, criticizing existing products for being “too slow” and stating that it is desired to have an improved product that works faster might be helpful for context. But unless the application further explains how better results and faster speeds are achieved, such a discussion of the background context has fairly limited value. Also, if the discussion of what was known is far more detailed than the discussion of what is supposedly new, this can have the undesired effect of suggesting that the inventors have yet to adequately develop the invention to a point of being patentable.

Omitting How It Works, or “Black Box” Gaps

A big mistake is failing to describe what the new invention is and how it works in sufficient detail. Often this means describing what is new too superficially so that it is no more than a plan for future invention or a mere statement of a problem to be solved or a desired result. Modern patent laws a premised on a quid pro quo: in exchange for disclosing how to make and use an invention, exclusive rights are granted for a limited time. But you cannot get exclusive patent rights by withholding the “secret” of how to make and use the invention.

Occasionally, this problem arises by placing important aspects of the invention in a “black box”. If key steps, ingredients, or structures are withheld from the disclosure contained in a patent application, then the patentability requirement of enablement (35 U.S.C. § 112(a)) is not met.

Stated more generally, it is necessary to provide a disclosure that enables someone of ordinary skill in the art to make and use the full scope of the invention as defined by the claims. The more one claims, the more one must enable. So a more limited disclosure might only support more limited claims. Sometimes this is a genus/species issue — a question of the sufficiency of disclosure of particular species to claim an entire genus. It is therefore necessary to have claims that are commensurate with the scope of the disclosure and not overbroad, or, from another perspective, to have a disclosure that is robust enough to support the desired claim scope.

One helpful thing (good) patent attorneys do is that they explain how inventions work in a understandable way. The technology may still be complicated. So the explanatory disclosure might not be entirely “easy” to read and understand. But inventors are sometimes able to devise working inventions without being able to translate that technology into words and drawings of the sort required for patent applications. It may be because they take some things for granted, or sometimes they might not even fully grasp what is different about their new invention from what was known before.

Lastly, there is still a requirement that the “best mode” of practicing an invention be disclosed. Applicants and inventors cannot disclose only what they know to be their second-best embodiment, while retaining the best for themselves.

Confusing Ambiguity with Breadth

While a broad claim is not necessarily ambiguous merely due to breadth, the reverse is problematic. Ambiguity does not lead to a broad scope of protection in a patent. This is a issue even experienced patent attorneys wrestle with and sometimes get wrong. By far, the most common source of trouble is the use of functional language or results-based claiming to try to obtain preemptive exclusive rights over significantly more than what was actually invented. This is one of the trickiest and most contested aspects of patent law and policy, so any brief discussion is hardly comprehensive.

Patent law looks to what is generally understood by given language. Using coined terminology and nonce words — often with vaguely functional connotations — without providing a sufficiently clear definition sometimes leads to impermissible ambiguity. Generic structural terminology as understood in a given technological field is often not the same thing as coined terminology not adopted into use generally in that field. For instance, the coined word “parkulator” does not convey any accepted structural meaning sufficient to use that term in patent claims (without a sufficient express definition). All too often, patent language is specifically drafted to avoid the use of generally-understood terms, which invites ambiguity problems. But you cannot benefit from avoiding accepted meanings if others cannot reasonably determine the scope of a claim due to intentional ambiguities.

There are many other examples as well, sometimes the result of errors and inconsistencies. For instance, if a claimed inventions rests on a parameter like an angle between two things, or a specific concentration of an ingredient or chemical element, or performing a process at a particular pressure, then it may be important to explain — consistently — how such parameters are measured or evaluated. The percentage of a material by weight or by volume might be quite different depending on the density of all the materials involved. Or the pressure might be measure in relative or absolute terms. And the location or direction in which an angle is measured might matter. Similar issues can arise through poor English translations too, which are treated as intentional choices. So translating a non-English word as a “spoon-digger” rather than a “backhoe” can be problematic.

Not Understanding Terms with Special Legal Meaning

There is a concept, sometimes referred to as the Dunning-Kruger Effect, that those who are incompetent in a given area tend to be ignorant of their own incompetence. In patent law, certain language has special legal significance. Rather than being given their ordinary, everyday meaning, certain words in certain contexts can be legal “terms of art” that have a special meaning. The paradox is that unless these special meanings in patent law are known, they might be inadvertently or unintentionally invoked.

Perhaps the most frequent errors of this sort arises with means-plus function claiming (35 U.S.C. § 112(f)). Under this format, an element of apparatus is claimed as “means for…[performing a stated function]” or “[functional descriptor] means for…[performing a stated function].” This type of claiming is currently permitted in the U.S. but is given a special interpretation: it literally covers only the disclosed corresponding structure, material, or acts, plus their known equivalents. Such an interpretation might be narrower than intended. It also might raise other problems if the corresponding structure is not clearly identified and disclosed.

Even patent attorneys can struggle with means-plus-function claiming. Courts have (somewhat controversially) said that if a claim limitation is drafted in the same format as a means-plus-function limitation and merely replaces the term “means” with a nonce word or generic placeholder like “module”, “mechanism”, “element”, or “device”, then a means-plus-function interpretation may still apply. Speaking in practical terms, claim limitations that rely too much on non-structural functional language might be interpreted as means-plus-function claiming.

Irrelevant Disclosure

Including a lot of unnecessary information just because it is available can be another problem. It wastes time and effort, and time is money when preparing patent applications. It can also obscure what is important and lead to longer (and more expensive) prosecution and examination after initial filing. Of course, knowing what sort of information is relevant and what is not is something that requires knowledge and experience. It can also be a matter of understanding the closest prior art, which is the next point.

Not Understanding the Closest Prior Art

Patentability largely depends on an invention being novel and nonobvious over what was already known. So, the catch is that to understand what is patentable it is unavoidably necessary to understand what is the closest prior art. Most of the time, that requires conducting a patentability search and analysis. However, applicants often wish to avoid the expense of a patentability search. This often leads to false economy, by requiring extensive post-filing efforts and expense to mitigate the problem of having not prepared a better initial application.

Knowing the closest prior allows a better patent application to be prepared — one that articulates what feature(s) of the invention differ from the closest prior art (and why that matters). For instance, a patentability search and analysis might suggest that additional technical information (another data table, figure, etc.) needs to be gathered for inclusion in a new application in order to sufficiently explain why the invention makes a patentable improvement. This may be the case where the prior art already achieves a similar result but in a different way, or where the prior art includes all the same parts but has them arranged or connected in a different way.

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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.