MPEP § 2173 — Claims Must Particularly Point Out and Distinctly Claim the Invention (Annotated Rules)

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

USPTO MPEP version: BlueIron's Update: 2025-12-31

This page consolidates and annotates all enforceable requirements under MPEP § 2173, including statutory authority, regulatory rules, examiner guidance, and practice notes. It is provided as guidance, with links to the ground truth sources. This is information only, it is not legal advice.

Claims Must Particularly Point Out and Distinctly Claim the Invention

This section addresses Claims Must Particularly Point Out and Distinctly Claim the Invention. Primary authority: 35 U.S.C. 112(b), 35 U.S.C. 112, and 35 U.S.C. 112(a). Contains: 4 requirements, 1 permission, and 3 other statements.

Key Rules

Topic

Alternative Limitations (MPEP 2173.05(h))

4 rules
StatutoryInformativeAlways
[mpep-2173-523991018b35ef5227e9ef4b]
Claims Must Particularly Point Out and Distinctly Claim the Invention
Note:
Patent claims must clearly and distinctly identify the invention as claimed by the inventor.

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 with 35 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.”

Jump to MPEP Source · 37 CFR 1.41(a)Alternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))Assignee as Applicant Signature
StatutoryInformativeAlways
[mpep-2173-9206cfdd951b03a6025deedb]
Claim Must Be Definite Under Section 112(b)
Note:
A claim that does not meet the definiteness requirement under section 112(b) or pre-AIA section 112, second paragraph is considered indefinite.

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 with 35 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.”

Jump to MPEP Source · 37 CFR 1.41(a)Alternative Limitations (MPEP 2173.05(h))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)
StatutoryRequiredAlways
[mpep-2173-fcf39ab211fd4cb9faba2cb1]
Claims Must Clearly Define Boundaries
Note:
Patent claims must be definite and clearly define the boundaries of protected subject matter for skilled artisans; otherwise, they must be amended or explained to meet this standard.

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.

Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))Determining Claim Definiteness (MPEP 2173.02)
StatutoryRequiredAlways
[mpep-2173-50a69310cd3d0a145a83b1a8]
Requirement for Clear Claim Boundaries
Note:
Applicants must respond to indefiniteness rejections by explaining claim definiteness or amending claims to clarify boundaries.

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.

Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))Determining Claim Definiteness (MPEP 2173.02)
Topic

Claim Form Requirements

3 rules
StatutoryRequiredAlways
[mpep-2173-0dc4427f22c364b179c0d23a]
Claims Must Particularly Point Out and Distinctly Claim the Invention
Note:
Patent claims must clearly and distinctly identify the inventor's claimed invention.

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 with 35 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.”

Jump to MPEP Source · 37 CFR 1.41(a)Claim Form RequirementsAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))
StatutoryRequiredAlways
[mpep-2173-7e5639ddf97b43a38377a345]
Definiteness Requirement for Claims
Note:
The claim language must clearly and precisely define the invention to comply with patent examination requirements.

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 with 35 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.”

Jump to MPEP Source · 37 CFR 1.41(a)Claim Form RequirementsAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))
StatutoryInformativeAlways
[mpep-2173-43f770e1a0b15a4544a6c5a0]
Claims Must Be Clear and Definite
Note:
The claims must clearly define the boundaries of the invention to inform the public about what constitutes infringement and meet patentability criteria.

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.

Jump to MPEP SourceClaim Form RequirementsLack of Antecedent Basis (MPEP 2173.05(e))Determining Claim Definiteness (MPEP 2173.02)
Topic

Determining Whether Application Is AIA or Pre-AIA

1 rules
StatutoryPermittedAlways
[mpep-2173-bc6c5cdb1d66515076c64df8]
Requirement for Clear Claim Language
Note:
The rule ensures that claims are clearly defined to meet patentability criteria and align with the specification's description.

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.

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIAAlternative Limitations (MPEP 2173.05(h))Lack of Antecedent Basis (MPEP 2173.05(e))

Citations

Primary topicCitation
Alternative Limitations (MPEP 2173.05(h))
Claim Form Requirements
Determining Whether Application Is AIA or Pre-AIA
35 U.S.C. § 112
Claim Form Requirements
Determining Whether Application Is AIA or Pre-AIA
35 U.S.C. § 112(a)
Alternative Limitations (MPEP 2173.05(h))
Claim Form Requirements
35 U.S.C. § 112(b)
Alternative Limitations (MPEP 2173.05(h))
Claim Form Requirements
37 CFR § 1.41(a)

Source Text from USPTO’s MPEP

This is an exact copy of the MPEP from the USPTO. It is here for your reference to see the section in context.

BlueIron Last Updated: 2025-12-31