What is a patent claim?

A patent claim defines the invention being protected by a patent or sought after in a patent application.  The patent owner can look at their patent claims and determine whether their competitors are infringing on their patent.  Competitors can review the claims to determine whether they are infringing on the patent and how to avoid infringement.  Let’s discuss the basics of a patent claim.

Structure of a claim

Each claim has a preamble, a transitional phrase, and a list of elements.  Each part of a claim serves a purpose in determining the scope of the claim.

Here is a sample claim for a wooden pencil.

The preamble determines the context of the claim.  In the example above, the preamble is “A writing instrument for generating marks on a surface.”  In this regard, the claim is directed to an apparatus.  The field of invention is writing instruments.  Sometimes, preambles limit the scope of the claim if they “life and breath” into the claim.  In other words, if the list of elements refers back to the verbiage of the preamble.

The transitional phrase may be comprising, consisting of, or consisting essentially of.  The most common transitional phrase is comprising and provides for the broadest interpretation of the claim.  The transitional phrases “consisting of” and “consisting essentially of” narrow the claims.  For example, the transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. And, the transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed invention.  See MPEP 2111.03.

The list of elements is the most important part of the claim.  Each word in the list of elements is significant.  For example, if the list of elements calls out a “carbon fiber” door, all doors made out of material other than carbon fiber do not infringe the claim.

Arrangement of the claims and numbering of the claim set

A claim can be an independent claim or a dependent claim.  An independent claim does not relate to or depend on any other claim.  See claims 1 and 4 above.  A dependent claim refers to another independent or dependent claim and recites all of the elements in that claim.  See claims 2, 3, and 5 above.   You can have multiple independent claims in one patent.  See claims 1 and 4 above.  You can also have multiple dependent claims that depend on an independent or dependent claim.  See claims 2 and 3 above.

All of the independent claims in a patent define the scope of patent protection afforded under the patent.  Claims 1 and 4 define the scope of protection for this claim set.

The claims are arranged in numerically ascending order starting from the number 1.

The claims collectively are referred to as the claim set.

Types of patent claims

A claim can protect an apparatus or a method.  We may refer to product patents, software patents, and process patents.  But, the bottom line is that all claims are either directed to an apparatus (i.e., a thing) or a method (i.e., a series of steps).

In an apparatus claim, the list of elements will be a list of parts of the product.  See claims 1-3 above.  In a method claim, the list of elements will be a list of steps.  See claims 4 and 5 above.

How to interpret the terms of a claim?

The words of a claim are given the ordinary and customary meaning based on the written description of the invention, the arguments presented to the examiner, and other outside sources as one having ordinary skill in the art would have understood those words at the time of the invention was made.

To understand what a patent claim covers, one needs to at the least read the patent application and the arguments presented by the inventor to the examiner.  If the patent application states that X means Y, then  X always means Y regardless of how others might understand the meaning of X.  For example, if a patent application states an elongate member is always greater than 12 inches long, then a member which is shorter than 12 inches long is not an elongate member.  The same result occurs if the inventor presented arguments to the examiner that an elongate member is always greater than 12 inches long in order to get the patent granted.

How to determine infringement of a claim?

To determine whether a competitor is literally infringing a claim, the competitor must incorporate each and every element in their product or service.  For example, looking at the table below, if a claim had elements A, B, and C, then to literally infringe the claim, the product has to incorporate elements A, B, and C as shown in Scenario 1.  If the product incorporated only elements A and B as in Scenario 2, then no literal infringement exists.  The products in Scenarios 3 and 4 do not literally infringe the claim because they are missing elements A and B.

If the product included additional features (represented by D in Scenario 5), literal infringement still exists because the product incorporates all of the elements A, B, and C.

And, if an element is not found in the product or service such as in Scenarios 2-4, infringement can still exist under the doctrine of equivalents.  Under the doctrine of equivalents, insubstantial differences are still covered by the claim if the product performs substantially the same function in substantially the same way to obtain the same result.  (i.e., function, way, result test).

To learn how to avoid patent infringement, read “Avoiding Patent infringement.”

How to write a patent claim?

The first step in writing a patent claim is to identify the point of novelty of the invention.  How is your invention different from the rest?  You should be able to describe your invention in a sentence or two which is your unique selling proposition.  All other aspects of your invention peripheral to or unrelated to the USP should not be listed as an element in the independent claim.

After you identify the point of novelty, you need to write the preamble, transitional phrase, and list of elements. The preamble ought to be straightforward.  If you can’t think of anything, just write “An apparatus” or “A method” for [insert the benefit of your invention].

The transition phrase should be “comprising.”  It is for 99.99 percent of most claims.

For the list of elements, think of things that are common to all products within the field of the invention.  For example, for writing instruments, most if not all writing instruments would have a protective sheath.  As such, although it limits the claim scope, in many ways, it doesn’t limit the claim scope in a significant way.  All competitors to the wooden pencil example above would have a protective sheath.

Learn more about the basics of writing a patent claim.