Patents Q&A

What Are Claims in a Patent?

Patents and patent applications typically have one or more “claims”. But what are claims? What is the significance of claims in patent law? This article offers a brief explanation of what they are and why they matter. It also explains some common misunderstandings and misconceptions about patent claims that can lead to great confusion.

Purpose of Claims

Patents provide exclusive rights in the form of a limited monopoly to an invention. Claims define the scope of exclusive legal rights in a granted patent or, in the case of a patent application, the scope of exclusive rights being sought. In other words, when thinking of patents as being premised on a quid pro quo, claims define the boundaries of the exclusive rights granted by a government to the patentee in exchange for disclosing an invention.

A common way to explain patent rights is to analogize them to real property (that is, land ownership). The claims are what establish the boundaries or metes-and-bounds of legal rights to a given patented invention. So claims are a bit like lot lines that establish the perimeter of a plot of land. Anything falling within the scope of a claim is protected. Just like the area within lot line boundaries belongs to the landowner.

Consider this simple guideline for granted patents: anything claimed is patented, and anything not claimed is not patented. In that sense, claims put others on notice of the scope of exclusive rights held by a patentee. And, when a new patent application is filed, the claims are the main focus of examination to determine if the invention (as claimed) is patentable. A patent is only being sought for what the claims of a given application recite.

Under U.S. patent law, claims are considered a part of the “specification” of a patent application. The basic requirements for claims are set forth in Section 112 of those patent statutes:

“The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.”

35 U.S.C. § 112(b)

When the U.S. patent laws set out what constitutes infringement of a “patented invention” (35 U.S.C. § 271). This is a reference to the claims. That is because the claims are what define the scope of the patented invention.

However, patent laws may differ between countries. For instance, the USA follows what is called peripheral claiming. Peripheral claims set forth the outermost boundaries of the exclusive rights with reasonable clarity, and anything outside the claims is generally not protected (with a rare exception under the doctrine of equivalents). But some other countries follow central claiming instead. Under central claiming regimes, the claims set out a basic inventive concept and the exclusive patent rights encompass an area that might extend beyond the literal scope of the claim language based upon the inventor(s)’s contribution over the prior art (as later determined by a court). Peripheral claiming makes the scope of rights more certain prior to an infringement lawsuit.


What claims say and how they say it varies. They are unique to each application or patent. They are also written by patent applications, who have considerable discretion over what they recite and how they are formulated. Claims are meant to define inventions, so they necessarily vary to reflect the particular subject matter of a given invention. But any given claim might define an invention broadly or narrowly in scope, relatively speaking.

In order for a patent application to be found patentable, its claims have to meet the requirements for patentability. Among other things, this means that the claims must distinguish the invention over the prior art. Accordingly, claims of a given application may try to distinguish the prior art by reciting elements (also called limitations) that go beyond what was already known.

Claims can be—and often are—amended, and may between an original application, a pre-grant published application, and/or a later-granted patent. Claims might also be canceled/deleted or new claims added during examination (which is also called “prosecution”). There are even procedures to amend or correct claims after a patent has issued. This means that the substantive content of the claims can change over time. Sometimes this means that a given claim is narrowed by amendment to establish patentability. This can give rise to prosecution history estoppel.

The interpretation or construction of terms in a patent claim is very important. For instance, certain terms of art may have special legal or technical meaning. The way claims are interpreted can vary greatly between different jurisdictions.


The format in which claims are written follow some general guidelines, even if their substantive content varies. For instance, they always appear at the very end of U.S. patents. They are each written as a single sentence. Parts of a claim may start on separate lines with special indenting to highlight distinct clauses. Although any given clause might contain multiple discrete limitations or elements. It is common for claims to use words like “wherein” and “comprising” that are not often used in everyday speech.

Means-plus-function (or step-plus-function) limitations are also a special type of claiming format permitted in the USA (35 U.S.C. § 112(f)). These limitations are interpreted to cover corresponding structures, materials, or acts disclosed elsewhere in the patent or application (and their known equivalents). Understanding when means-plus-function claiming is invoked or applies, and how to properly interpret the scope of that limitation, is sometimes difficult. But one rule is clear. There can be no “single means” claims, because a claim that contains only a single limitation in means-plus-function format would be an impermissible central claim rather than a peripheral claim.

A patent may have only one, a few, or very many claims. Typically, each claim is separately numbered. Some claims may refer back to prior claims by number. However, U.S. design patents have only a single unnumbered claim. U.S. plant patents also have only a single claim but it is numbered. Regardless of how many are present, each claim is generally considered separately. In this respect, claim numbering helps indicate how many different definitions of a given invention must be considered when evaluating either patentability/validity or infringement.

Types of Claims

Independent Claims vs. Dependent Claims

Claims can be either independent or dependent (35 U.S.C. § 112(c)). An independent claim stands on its own. In contrast, a dependent claim refers back to a prior claim (by number) and incorporates the limitations of all base claims (35 U.S.C. § 112(d)). The status of a given claim as either independent or dependent can have important legal significance for patentability/validity and other analyses.

The following is an example of a set of four claims in which claims 1 and 4 are independent claims and claims 2 and 3 are dependent claims:

1. An apparatus comprising an element A, an element B, and an element C.
2. The apparatus of claim 1, wherein the element A and the element B are each made of metal.
3. The apparatus of claim 2, wherein the element A is welded to the element B.
4. A method comprising step X, step Y, and step Z.

In the example above, claim 2 depends from claim 1. Because of that dependency, claim 2 incorporates all of the elements or limitations of independent base claim 1 and further adds an additional limitation. Claim 3 depends from claim 2, which in turn depends from claim 1. This means claim 3 incorporates all of the limitations of both base claims 1 and 2 and further adds an additional limitation. Claim 4 is another independent claim, which stands on its own. The limitations of claims 1-3 are not incorporated into claim 4.

Claim 1 of any patent or patent application is always an independent claim, because there is no prior claim to refer back to. Any claims that follow claim 1 might also be independent, or might be dependent. This depends on how they are written. Patentees have considerable latitude over how many claims and what types of claims are present. Although dependent claims are not permitted in U.S. design or plant patents.

When analyzing patents and patent applications, independent claims usually always require consideration, while dependent claims might not in some situations. For example, when assessing potential infringement, a dependent claim can only be infringed if its independent base claim is also infringed. But an independent claim might be infringed even if no dependent claim is infringed. So, in many contexts, dependent claims can be thought of as reciting optional features. Yet dependent claims might still be important. Validity and patentability are assessed on a claim-by-claim basis, so while an independent claim might be unpatentable (or invalid), dependent claims depending from it might still be patentable (or valid).

Multiple Dependent Claims

Multiple dependent claims are also possible (35 U.S.C. § 112(e)). A multiple dependent claim refers back to multiple prior claims in the alternative. Examples of multiple dependent claim references are “the method of any preceding claim” or “the apparatus of claim 1 or 2” or “the system of any of claims 2, 4, and 8.” The easiest way to think about multiple dependent claims is that they always present a single claim that is equivalent to having a number of separate dependent claims that each depend from different base claims.

Omnibus Claims

An omnibus claim makes a general incorporation into a claim of some other disclosure, without specifically defining the invention or even a central inventive concept. An example is “The apparatus substantially as shown and described.” Omnibus claims are permitted in some jurisdictions, but not in U.S. utility patents. Except U.S. design patents always have only a single omnibus claim reciting the design “as shown and described” (37 C.F.R. § 1.153(a)). And U.S. plant patents always have a single claim in omnibus format that states “as described and illustrated” (37 C.F.R. § 1.164)—although plant patents cover only asexual reproduction of the patented plant, through grafting, cuttings, etc., which distinguishes their claims from true omnibus claims in terms of their effect.

Other Types

There are a number of other names given to certain types of claims, often more informally. For instance, Jepson claims specifically identify the point of novelty (in a manner called two-part form in many jurisdictions), combination claims recite a particular combination of components, a Beauregard claim recites a computer-readable medium on which computer program instructions are encoded, product-by-process claims recite an apparatus in terms of how it is made, etc.

Difference Between Claims and Other Disclosures

One of the most important things to understand is that the claims of a given patent—and not other parts of a patent like the detailed description or drawings— define exclusive rights to a patented invention. As already mentioned, what is claimed is patented and what is not claimed is not patented. This means it is possible to have unclaimed disclosures in a given patent. For instance, a patent might include a drawing illustrating a prior art device but not claim it. In other cases, a patent might claim only one or a few particular embodiments or “species” of an invention and not a generic invention (or entire “genus”).

When trying to understand if their is risk of infringing someone else’s patent, a mistake frequently made by people unfamiliar with patent law is to look at the drawings or some other text in the specification (like the detailed description section) and assume that any and all such disclosures are “patented”. That is incorrect. Only the claims define the patented invention. There are many reasons why there might be unclaimed subject mater disclosed in a patent—including a patent office determining that some aspects were or are not patentable. But often those reasons are unimportant. It is the claims, as properly construed, that define the scope of the patentee’s exclusive rights.

In contrast, if a given prior art patent or published patent application is cited as prior art, it usually makes no difference whether the relevant prior art teachings were claimed or not. Most of the time the claims are irrelevant to the value of a given reference as prior art—with some exceptions for situations like double patenting.

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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.