Skip to content

US patent law

35 U.S.C., annotated: US patent law section by section

By , Co-founder, PatentAssist.ai
Updated

Title 35 of the United States Code is the US patent statute. Most statute sites print the text and stop there. This reference gives you the current text of the 34 sections that come up most in drafting, prosecution and litigation, each with a plain-English summary, the cases that shape how it is applied, the 37 CFR rules and MPEP sections that implement it, and notes from practice.

Quick answer

  • What it is: the federal patent statute, in five parts, from the USPTO's organization (sections 1 to 42) to international design applications (sections 381 to 390).
  • The core four: 101 (eligibility), 102 (novelty), 103 (obviousness) and 112 (disclosure and claims).
  • Below the statute: 37 CFR holds the USPTO's binding rules; the MPEP tells examiners how to apply them.
  • AIA or pre-AIA: any claim with an effective filing date on or after March 16, 2013 puts the application under the first-inventor-to-file rules.
  • Currency: text current through Public Law 119-124 (October 15, 2026), checked October 26, 2026.

What Title 35 is

Title 35 is the Patent Act. Its current structure comes from the Patent Act of 1952, and it has been amended many times since, most heavily by the Leahy-Smith America Invents Act (Pub. L. 112-29, signed September 16, 2011). People cite it as “35 U.S.C. 112” or “35 U.S.C. § 112”; the USPTO and the MPEP usually leave out the section sign. Subsections are cited in brackets, so 35 U.S.C. 112(b) is the definiteness requirement and 35 U.S.C. 102(b)(1)(A) is the grace period for the inventor's own disclosures.

The title has five parts. Nearly everything an applicant deals with day to day sits in Part II (getting a patent) and Part III (enforcing and challenging one).

Part Sections What it covers
Part I
United States Patent and Trademark Office 		1–42
ch. 1–4 		The USPTO, its officers and the PTAB, practitioners, and fees (section 41).
Part II
Patentability of Inventions and Grant of Patents 		100–212
ch. 10–18 		What can be patented, the application, examination, appeal, issue, term, designs, plants, secrecy and foreign filing licenses, and Bayh-Dole.
Part III
Patents and Protection of Patent Rights 		251–329
ch. 25–32 		Reissue and correction, ownership, infringement, remedies, reexamination, inter partes review and post-grant review.
Part IV
Patent Cooperation Treaty 		351–376
ch. 35–37 		PCT applications filed in or designating the United States, and the US national stage.
Part V
The Hague Agreement Concerning International Registration of Industrial Designs 		381–390
ch. 38 		International design applications under the Hague Agreement.

How Title 35 relates to 37 CFR and the MPEP

US patent practice runs on three layers of text, plus the case law that interprets them. The statute sets the requirement, the regulations set the procedure and the deadline, and the MPEP tells the examiner how to apply both. Take a foreign priority claim: section 119(b) says the claim must be filed “at such time during the pendency of the application as required by the Director”, 37 CFR 1.55(d) fixes that time at the later of 4 months from filing or 16 months from the foreign filing, and MPEP 213 explains how examiners check it.

Source What it is Made by Who it binds
35 U.S.C. (Title 35) The statute: what can be patented, what an application must contain, examination, term, infringement and remedies. Congress Everyone: the USPTO, courts, applicants and the public.
37 CFR (parts 1, 3, 5, 11, 41, 42) The USPTO's regulations: deadlines, fees, forms, papers, appeals and PTAB trials. USPTO rulemaking under 35 U.S.C. 2(b)(2) Applicants and the USPTO, as long as the rule is consistent with the statute.
MPEP The Manual of Patent Examining Procedure: how examiners apply the statute, the rules and the case law. USPTO (current: Ninth Edition, Revision 01.2024) Instructions to examiners. Not law, and courts are not bound by it, but it is how your application will be examined.
Case law Supreme Court and Federal Circuit decisions interpreting the statute, such as the eligibility test under section 101. Federal courts Courts and the USPTO. Where the MPEP and a newer decision differ, the decision controls.

Two consequences matter in practice. First, a rule cannot override the statute, so when a USPTO requirement looks harsher than the section it implements, read the section. Second, the MPEP lags the case law. The current edition is Revision 01.2024, and the USPTO issues memoranda in between, as it has repeatedly on subject matter eligibility, so check the USPTO's guidance pages as well as the manual.

AIA and pre-AIA: which version applies

The America Invents Act rewrote much of Title 35, and its changes took effect in stages. The biggest one, the move from first-to-invent to first-inventor-to-file, applies to any application that contains, or ever contained, a claim with an effective filing date on or after March 16, 2013, or that claims the benefit of an application that did. Those applications, and the patents issued on them, are “AIA applications” and are examined under the current section 102 and section 103. Applications whose claims all have effective filing dates before March 16, 2013 stay under the pre-AIA versions for life.

What changed for novelty is the reference date. Pre-AIA law measured prior art from the date of invention, allowed an applicant to swear behind a reference with a 37 CFR 1.131 declaration of earlier invention, and resolved disputes between rival inventors in interferences. AIA law measures everything from the effective filing date. The only protection for the inventor's own earlier disclosures is the 1-year grace period exceptions in section 102(b), claimed with a 37 CFR 1.130 declaration. Interferences gave way to derivation proceedings under section 135.

Other AIA changes have their own dates. For applications filed on or after September 16, 2012, an assignee can be the applicant and the inventor's oath was simplified (section 115). Inter partes review replaced inter partes reexamination on the same date, for all patents (section 311). Best mode stopped being a ground of invalidity in litigation commenced on or after September 16, 2011 (section 282), though it is still a requirement of section 112(a). Post-grant review (section 321) is available only for AIA patents.

Mixed families need care. A continuation-in-part filed on or after March 16, 2013 that adds even one claim relying on new matter becomes an AIA application as a whole. When a nonprovisional filed on or after that date claims priority to an application filed before it, 37 CFR 1.55 and 1.78 require a statement if it contains, or ever contained, a claim with an effective filing date on or after March 16, 2013 (MPEP 2159). Every section page below quotes the current, AIA text, and notes the pre-AIA position where it still matters.

Annotated sections

34 sections, grouped by topic in the order they appear in the title. Each page has the statute text, a plain-English summary, key cases, related rules and MPEP sections, and practical notes.

Fees · Part I

Section Official heading What it covers
§ 41 Patent fees; patent and trademark search systems Patent fees

Patentability · Part II

Section Official heading What it covers
§ 100 Definitions Definitions
§ 101 Inventions patentable Patent-eligible subject matter
§ 102 Conditions for patentability; novelty Novelty and prior art
§ 103 Conditions for patentability; non-obvious subject matter Obviousness

The application · Part II

Section Official heading What it covers
§ 111 Application Application, including provisionals
§ 112 Specification Specification and claims
§ 113 Drawings Drawings
§ 115 Inventor’s oath or declaration Inventor's oath or declaration
§ 116 Inventors Joint inventors
§ 119 Benefit of earlier filing date; right of priority Priority and provisional benefit
§ 120 Benefit of earlier filing date in the United States Continuing applications
§ 121 Divisional applications Restriction and divisionals
§ 122 Confidential status of applications; publication of patent applications Confidentiality and publication

Examination and appeal · Part II

Section Official heading What it covers
§ 131 Examination of application Examination
§ 132 Notice of rejection; reexamination Office actions and RCEs
§ 134 Appeal to the Patent Trial and Appeal Board Appeal to the PTAB

Issue, term and term extensions · Part II

Section Official heading What it covers
§ 151 Issue of patent Issue of patent
§ 154 Contents and term of patent; provisional rights Patent term and adjustment
§ 156 Extension of patent term Patent term extension

Design patents · Part II

Section Official heading What it covers
§ 171 Patents for designs Design patents
§ 173 Term of design patent Design patent term

Foreign filing licenses · Part II

Section Official heading What it covers
§ 184 Filing of application in foreign country Foreign filing license

Correcting a patent · Part III

Section Official heading What it covers
§ 251 Reissue of defective patents Reissue

Infringement and defenses · Part III

Section Official heading What it covers
§ 271 Infringement of patent Infringement
§ 273 Defense to infringement based on prior commercial use Prior commercial use defense
§ 282 Presumption of validity; defenses Presumption of validity

Remedies · Part III

Section Official heading What it covers
§ 284 Damages Damages
§ 285 Attorney fees Attorney fees
§ 286 Time limitation on damages Time limit on damages
§ 287 Limitation on damages and other remedies; marking and notice Marking and notice

Post-grant challenges at the PTAB · Part III

Section Official heading What it covers
§ 311 Inter partes review Inter partes review
§ 321 Post-grant review Post-grant review

PCT national stage · Part IV

Section Official heading What it covers
§ 371 National stage: Commencement PCT national stage

Reading a section well

Read the whole section, not the quoted fragment in an office action. Exceptions often sit a subsection away from the rule: the grace period in section 102(b) qualifies the prior art definition in 102(a), and the safe harbor in section 121 applies only to divisionals filed as a result of a restriction requirement.

Then check the definitions in section 100 and the rule that implements the section. Deadlines are almost never in the statute itself. Section 119 says a priority claim must be made in the time the Director requires; the actual 4- and 16-month deadline is in 37 CFR 1.55. Section 133 allows up to 6 months to reply to an office action; the 3-month shortened period and the extension fees come from the rules and the action itself.

Finally, check the date. Our text is current through Public Law 119-124. If a statute page anywhere does not tell you how current it is, treat it as a starting point, not an answer.

Where PatentAssist fits

Most section 112 problems start in the first draft. PatentAssist.ai drafts claims, the detailed description, the abstract and drawings in USPTO format from your invention disclosure, so you start from a specification with support for fallback claims instead of a blank page. Its prior-art search covers USPTO, EPO and Indian records, which helps you see the section 102 and 103 landscape before you file. It does not answer USPTO office actions or handle PTAB proceedings; that work stays with you or your registered practitioner.

Try drafting free for 7 days Search US patents

More USPTO guides

All guides, by patent office

35 U.S.C.: frequently asked questions

What is 35 U.S.C.?

35 U.S.C. is Title 35 of the United States Code, the federal patent statute. It sets out what can be patented (sections 101 to 103), what an application must contain (sections 111 to 122), how the USPTO examines and grants patents, how long a patent lasts (section 154), what counts as infringement (section 271) and the remedies for it (sections 281 to 299), as well as inter partes review and post-grant review at the Patent Trial and Appeal Board.

What is the difference between 35 U.S.C., 37 CFR and the MPEP?

35 U.S.C. is the statute passed by Congress. 37 CFR contains the USPTO's regulations, which fill in deadlines, fees and procedure, such as the 4- and 16-month deadline for priority claims in 37 CFR 1.55. The MPEP is the USPTO's manual telling examiners how to apply both. The statute and the rules are binding law; the MPEP is guidance, though in practice it is how your application will be examined.

What do 35 U.S.C. 101, 102, 103 and 112 mean?

They are the four patentability requirements examiners cite most. Section 101 covers eligible subject matter and utility, section 102 novelty and what counts as prior art, section 103 obviousness, and section 112 the disclosure and claim requirements: written description, enablement, best mode, definite claims and means-plus-function claims.

What is the difference between AIA and pre-AIA?

The Leahy-Smith America Invents Act of 2011 moved the US from first-to-invent to first-inventor-to-file. AIA sections 102 and 103 apply to applications that contain, or ever contained, a claim with an effective filing date on or after March 16, 2013. Applications whose claims all date from before then are examined under the pre-AIA versions, where prior art was measured from the date of invention.

How long does a US patent last?

A utility patent lasts 20 years from its US filing date, or from the filing date of the earliest US nonprovisional or PCT application it claims under section 120, as long as maintenance fees are paid (35 U.S.C. 154). The term can be lengthened by patent term adjustment for USPTO delay and, for products that needed FDA approval, by patent term extension under section 156. A design patent filed on or after May 13, 2015 lasts 15 years from grant (section 173).

Is the statute text on these pages official?

The text is quoted from the United States Code published by the Office of the Law Revision Counsel at uscode.house.gov, current through Public Law 119-124 (October 15, 2026). Editorial notes and footnotes are left out. Each section page links to the official page for that section; check it before relying on the text.

Sources: Title 35, United States Code, Office of the Law Revision Counsel, current through Pub. L. 119-124; 37 CFR (eCFR), parts 1, 5, 41 and 42; MPEP, Ninth Edition, Revision 01.2024; USPTO, inter partes review. This reference is general information, not legal advice. For a decision on a real application or patent, ask a registered patent attorney or agent.

Statute text from the United States Code published by the Office of the Law Revision Counsel of the U.S. House of Representatives (uscode.house.gov). Text contains those laws in effect through Public Law 119-124 (October 15, 2026). Editorial notes and footnotes are omitted. The annotations are general information, not legal advice; check the official text and a registered patent practitioner before relying on them.

Looking for Indian law? Read the Patents Act, 1970, section by section.