MPEP § 2173 — Claims Must Particularly Point Out and Distinctly Claim the Invention

Ninth Edition, Revision 01.2024 · last revised R-10.2019

Optimizing patent quality by providing clear notice to the public of the boundaries of the inventive subject matter protected by a patent grant fosters innovation and competitiveness. Accordingly, providing high quality patents is one of the agency’s guiding principles. The Office recognizes that issuing patents with clear and definite claim language is a key component to enhancing the quality of patents and raising confidence in the patent process.

35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph requires that a patent application 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. (Note that although pre-AIA 35 U.S.C. 112, second paragraph, uses the phrase “which applicant regards as his invention,” pre‑AIA 37 CFR 1.41(a) provides that a patent is applied for in the name or names of the actual inventor or inventors.) In patent examining parlance, the claim language must be “definite” to comply with35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. Conversely, a claim that does not comply with this requirement of 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph is “indefinite.”

The primary purpose of this requirement of definiteness of claim language is to ensure that the scope of the claims is clear so the public is informed of the boundaries of what constitutes infringement of the patent. A secondary purpose is to provide a clear measure of what the inventor or a joint inventor regards as the invention so that it can be determined whether the claimed invention meets all the criteria for patentability and whether the specification meets the criteria of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph with respect to the claimed invention.

It is of utmost importance that patents issue with definite claims that clearly and precisely inform persons skilled in the art of the boundaries of protected subject matter. Therefore, claims that do not meet this standard must be rejected under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph as indefinite. Such a rejection requires that the applicant respond by explaining why the language is definite or by amending the claim, thus making the record clear regarding the claim boundaries prior to issuance. As an indefiniteness rejection requires the applicant to respond by explaining why the language is definite or by amending the claim, such rejections must clearly identify the language that causes the claim to be indefinite and thoroughly explain the reasoning for the rejection.