USPTO Patent Prosecution Rules

37 CFR Part 1 is the USPTO's complete procedural rulebook for patent prosecution — the process of applying for, examining, appealing, and maintaining a U.S. patent. It governs everything from application filing format and claim requirements to the back-and-forth with an examiner over patentability, appeals to the Patent Trial and Appeal Board (PTAB), and the maintenance fees needed to keep an issued patent alive. Since the Leahy-Smith America Invents Act (AIA) took effect in 2013, the U.S. operates as a first-inventor-to-file system: priority goes to the first to file, not the first to invent — aligning U.S. practice with the rest of the world.

Current Rule (2026)

What This Rule Does

37 CFR Part 1 is the USPTO's complete rulebook for patent prosecution — the process of applying for, examining, appealing, and maintaining a U.S. patent. It covers everything from where to mail a patent application to the precise format of claims, the procedure for responding to an examiner's rejection, and the rules for challenging a granted patent through reexamination. Every inventor, patent attorney, and patent agent interacting with the USPTO does so under these rules.

The patent prosecution process is a dialogue between the inventor (or their representative) and a patent examiner: the applicant files an application, the examiner evaluates it against patentability requirements (novelty, non-obviousness, written description), and the parties exchange arguments — typically over several rounds — until a patent issues, an appeal is filed, or the application is abandoned. Part 1 sets the timing, content requirements, and procedural rights for every step.

Since the Leahy-Smith America Invents Act (AIA) took effect in 2013, the U.S. patent system operates as a first-inventor-to-file system (§ 1.109): priority among competing inventors is determined by who first filed a patent application, not who first made the invention. This aligns U.S. practice with the rest of the world and eliminated much of the complex interference practice that preceded the AIA.

Key Provisions

Application Requirements (Subpart A and B)

• § 1.14 — Patent applications preserved in confidence: unpublished applications are confidential; the public cannot access an application until it is published (typically 18 months after the earliest priority date) or the patent issues; applicants may request non-publication if they do not intend to file abroad
• § 1.16 — Filing fees: basic filing fee for a utility application is approximately $350 for large entities, $175 for small entities (businesses under 500 employees), and $70 for micro entities (individuals with income below three times the U.S. median household income who have not filed more than four other applications)
• § 1.109 — Effective filing date under the AIA: the "effective filing date" for a claimed invention is the earliest actual or provisional filing date for which the claim has benefit; under the first-inventor-to-file system, this determines priority when two inventors claim the same invention

Examination Procedures (Subpart B)

• § 1.104 — Nature of examination: the examiner must make a thorough study of the application and search available prior art; the examiner shall point out any grounds of rejection and explain the relevance of any prior art cited; examiners may issue non-final or final actions
• § 1.111 — Reply to non-final Office action: after receiving a rejection or objection, the applicant must reply within 3 months of the mailing date (extendable up to 6 months on payment of extension fees); a response must address every rejection and objection raised; failure to respond results in abandonment
• § 1.112 — Reconsideration before final action: after a timely response to a non-final action, the examiner reconsiders and re-examines; the examiner may issue another non-final action, a final action, or allow the application
• § 1.113 — Final rejection: typically issued on the second or any subsequent examination; after a final rejection, the applicant's options are limited — an amendment can only be filed if it clearly places the application in condition for allowance, or the applicant must file an RCE or appeal
• § 1.114 — Request for Continued Examination (RCE): after final rejection, applicants may file an RCE with a new submission and fee to reopen prosecution; this is one of the most common ways to continue prosecution after a final rejection and gives the applicant additional opportunities to amend claims or provide arguments

Affidavits and Evidence (Subpart B)

• § 1.130 — AIA § 102(b) prior disclosure safe harbor affidavit: an inventor who disclosed the invention publicly less than one year before the filing date can submit an affidavit to disqualify that disclosure as prior art; this protects inventors who presented at conferences or published papers before filing
• § 1.131 — Antedating prior art: an applicant may submit an affidavit showing prior invention (for pre-AIA applications) or a prior disclosure exception (for AIA applications) to disqualify cited prior art
• § 1.132 — Traversing rejections with evidence: any evidence submitted to dispute a rejection that is not otherwise provided for must be by affidavit or declaration under oath; expert declarations are commonly used to address obviousness rejections

Patent Term and Maintenance

• Subpart F (23 sections) — Patent term adjustment (PTA): utility patents are granted for 20 years from the earliest filing date; if USPTO delays in examination (failure to act within 14 months of filing, or 4 months of a response) add to the term; applicant delays subtract from the term; PTA compensates for USPTO processing delays
• 35 U.S.C. § 154 (implemented via Part 1) — Patent term: 20 years from filing; design patents 15 years from grant; plant patents 20 years from filing

Reexamination and Post-Grant Review

• Subpart D (15 sections) — Ex parte reexamination: any person (including the patent owner or third parties) may file a request for reexamination based on prior art patents or printed publications that raise a substantial new question of patentability; the request costs $12,000; if granted, the USPTO reexamines the patent claims and may confirm, narrow, or cancel them
• Subpart H (40 sections) — Inter partes reexamination: the predecessor to inter partes review (IPR); applies to patents filed before the AIA's September 2012 effective date; both the requester and patent owner can participate in the reexamination before the examiner

International Filing

• Subpart C (46 sections) — PCT (Patent Cooperation Treaty) international applications: U.S. applicants can file a single international application that reserves the right to enter the national phase in up to 150+ countries within 30 months of the earliest priority date; the USPTO serves as a receiving office, international searching authority, and international preliminary examining authority for PCT applications
• Subpart I (31 sections) — International design applications under the Hague Agreement: industrial designs can be registered internationally through WIPO, with the USPTO acting as an office of indirect filing for U.S. applicants

Biotechnology

• Subpart G (20 sections) — Biotechnology invention disclosures: special deposit and disclosure requirements for biological material that cannot be fully described in writing; specifies Budapest Treaty depository requirements for microorganisms, cells, and genetic sequences

How It Affects You

If you're an inventor considering a patent: The first critical step is filing a patent application promptly — under the AIA, the first person to file wins in the event of competing inventors. You can file a provisional application (§ 1.53) for a lower fee (~$350 for large entities, $175 small, $70 micro) to secure a priority date, then file a non-provisional application within 12 months that claims priority to the provisional. The provisional buys time to test the market while preserving your filing date.

If you receive an Office action (rejection): You have 3 months to respond without an extension fee. Extensions cost $100–$1,000+ depending on how long you need. Non-final rejections are easier to overcome — the examiner hasn't committed to rejecting you. After a final rejection, your options narrow: argue (with limited ability to add new claims), file an RCE to reopen prosecution, or appeal to the Patent Trial and Appeal Board (PTAB).

If you want to challenge someone else's patent: You can file an ex parte reexamination request based on prior art for $12,000 — but you have limited participation rights once it's granted. For post-AIA patents, inter partes review (IPR) at PTAB is generally the preferred challenge mechanism (addressed in 37 CFR Part 42, not Part 1).

If you're a small company or individual inventor: The small entity fee discount (50%) is available to independent inventors and businesses with under 500 employees that have not transferred rights to a large entity. The micro entity discount (80%) is available to inventors with income below three times U.S. median household income who have not filed more than 4 prior U.S. patent applications (excluding PCT and provisional). Claiming these discounts when ineligible is fraud.

If you filed abroad before filing in the U.S.: You can claim foreign priority under 35 U.S.C. § 119 as long as you file in the U.S. within 12 months of your foreign filing date. The foreign application gives you a priority date — the U.S. application will be examined as if it was filed on the date of the foreign application. This is critical because the first-to-file rule means your effective priority date determines patentability.

Statutory Authority

This rule implements:

• 35 U.S.C. § 2 — USPTO authority to establish regulations governing the conduct of proceedings in the Office
• 35 U.S.C. § 111 — Application for patent: requirements for a complete application (specification, claim or claims, drawings where necessary, oath or declaration)
• 35 U.S.C. § 119 — Benefit of earlier filing date in foreign country and certain United States applications (12-month foreign priority)
• 35 U.S.C. § 122 — Confidential status of applications; publication: applications published 18 months after filing; exceptions for applicants who do not file abroad

Ex Parte Appeals to PTAB (37 CFR Part 41)

When an examiner finally rejects a patent application and the applicant cannot overcome the rejection through argument or claim amendment, the applicant's administrative remedy is an ex parte appeal to the Patent Trial and Appeal Board (PTAB) under 37 CFR Part 41 — Practice Before the Patent Trial and Appeal Board. This is the standard appeal path for any rejected patent application — not a challenge to someone else's patent (that is Part 42 IPR/PGR), but a review of the examiner's own rejections.

Key provisions of the ex parte appeal procedure (Subpart B, §§ 41.30–41.54):

• § 41.31 — Who may appeal and timing: any applicant whose claims have been twice rejected (typically after a non-final rejection followed by a final rejection) may appeal to PTAB; the notice of appeal must be filed within the time set for response to the final rejection (typically 3 months from the final rejection, extendable); the appeal fee must accompany the notice
• § 41.37 — Appeal brief: the appellant must file an appeal brief within 2 months of filing the notice of appeal; the brief must identify each claim on appeal, the rejection being appealed, and the argument for each rejection (separately for each rejection); failure to file a timely brief results in dismissal of the appeal; the brief filing fee is currently $0 but an "appeal forwarding fee" is required when the examiner answers
• § 41.39 — Examiner's answer: the primary examiner may file a written answer to the appeal brief (within a time set by the Director); the examiner's answer may designate a new ground of rejection (which reopens prosecution rather than continuing the appeal); the examiner's answer is the examiner's last word before PTAB takes jurisdiction
• § 41.41 — Reply brief: appellant may file one reply brief to the examiner's answer within 2 months; the reply brief may only respond to new points raised in the examiner's answer (not re-argue claims already addressed in the appeal brief); no further briefing permitted
• § 41.47 — Oral hearing: appellant may request an oral hearing before PTAB; the board notes that an appeal decided on briefs alone receives the same consideration as one decided after oral argument — hearings are primarily useful for complex factual disputes or where in-person presentation adds clarity
• § 41.50 — Board decisions: PTAB may affirm (sustain the rejection, application abandoned unless appeal continues to Federal Circuit), affirm in part, or reverse (overruling the examiner's rejection; claims return to the examiner for allowance). PTAB may also designate a new ground of rejection sua sponte — this is important because a new ground of rejection remands to the examiner with the applicant getting a fresh chance to respond, rather than a direct affirmance/reversal
• § 41.52 — Rehearing: a single request for rehearing may be filed within 2 months of the Board's decision
• § 41.54 — After the decision: jurisdiction passes back to the examiner; if reversed, the examiner allows the claims; if affirmed, the applicant may appeal to the Court of Appeals for the Federal Circuit under 35 U.S.C. § 141, or file a new application with a continuation

The practical significance: PTAB ex parte appeals reverse the examiner in approximately 20–25% of cases in recent years — a non-trivial win rate that makes appeals worthwhile for applications with commercially significant claims. PTAB decisions are precedential when designated as such by the Chief APJ, creating patent law precedent on claim construction and patentability standards. The appeal process typically takes 12–24 months from filing the notice of appeal to a decision.

PTAB Trial Proceedings (37 CFR Part 42)

The Patent Trial and Appeal Board (PTAB) adjudicates two primary post-grant review proceedings that allow third parties to challenge the validity of issued patents — a major alternative to district court litigation. These proceedings are governed by 37 CFR Part 42 — Trial Practice Before the Patent Trial and Appeal Board.

Inter Partes Review (IPR) — Subpart B (§§ 42.100–42.123): A petitioner (any person who is not the patent owner) may challenge one or more patent claims on the grounds that they are anticipated (§ 102) or rendered obvious (§ 103) by prior art consisting of patents or printed publications. Key procedural points:

• § 42.100 — IPR is a trial subject to general PTAB procedures; claim construction uses the same standard as a district court civil action (ordinary and customary meaning in light of prosecution history); pendency after institution is normally no more than one year (extendable 6 months for good cause)
• § 42.101 — Who may petition: any person other than the patent owner may petition for IPR; a person who has been served with a complaint alleging infringement has only one year from service to file an IPR petition on that patent — missing this deadline bars IPR on that patent
• § 42.104 — Contents of petition: must identify all real parties in interest, the specific claims challenged, the statutory grounds, and claim charts mapping prior art to each claim element; must include supporting expert declarations
• § 42.107 — Patent owner preliminary response: the patent owner may file a preliminary response within 3 months of the petition; PTAB considers this before deciding whether to institute
• § 42.108 — Institution decision: PTAB institutes IPR if the petition shows a reasonable likelihood that at least one challenged claim is unpatentable; institution is decided by PTAB panels of three Administrative Patent Judges (APJs)
• § 42.121 — Motion to amend: the patent owner may file one motion to amend the patent (substituting narrower claims) during the IPR proceeding; the motion must demonstrate patentability of the proposed substitute claims

Post-Grant Review (PGR) — Subpart C (§§ 42.200–42.224): PGR allows any person (other than the patent owner) to challenge any claim of an AIA-eligible patent on any ground of invalidity — including § 101 subject matter eligibility, § 112 written description, and prior art. PGR must be filed within 9 months of the patent's grant or reissuance. The standard for institution is higher than IPR: the petition must show it is "more likely than not" that at least one claim is unpatentable (§ 42.208). After the 9-month window closes, IPR is the available post-grant challenge mechanism.

Covered Business Method (CBM) review — Subpart D: a transitional program (now expired for new petitions) that allowed challenges to certain financial-method patents that were issued before AIA's effective date; modeled on PGR but available to defendants sued for patent infringement.

Derivation proceedings — Subpart E (§§ 42.400–42.412): available for patents claiming the same invention, to determine whether the named inventor in one patent derived the claimed invention from another inventor. This is the post-AIA replacement for interference proceedings; rarely used.

The practical effect of PTAB proceedings: IPR has become the dominant mechanism for challenging patent validity in high-stakes patent disputes. Tech and pharmaceutical companies routinely file IPR petitions either defensively (when sued for infringement) or offensively (to clear blocking patents). PTAB's final written decisions are appealable to the Court of Appeals for the Federal Circuit (§ 42.5 incorporating 35 U.S.C. § 141); many significant patent validity questions now flow through PTAB before reaching the Federal Circuit. The one-year bar for accused infringers (§ 42.101(b)) is a critical deadline in patent litigation strategy — once waived, IPR is unavailable as a parallel validity challenge.

Recent Rulemakings

• AIA implementation rules (2012–2013): USPTO issued multiple rules implementing the Leahy-Smith America Invents Act, including the first-inventor-to-file transition, inter partes review procedures, covered business method review, and derivation proceedings — the most comprehensive patent rule overhaul since 1952.
• Micro entity status (2013): USPTO implemented the AIA's micro entity fee category, providing an 80% fee reduction for qualifying individual inventors — a significant reduction in barriers for independent inventors.
• Patent term adjustment final rule (2012): Revised PTA calculation to more accurately compensate applicants for USPTO delays, addressing a court ruling that found the prior formula undercompensated patent owners.

Recent Developments

• AI inventorship and patent eligibility (2024–2026): The Federal Circuit's Thaler v. Vidal (2022) held that AI systems cannot be named inventors on U.S. patents — only natural persons qualify. USPTO issued guidance in 2024 addressing AI-assisted inventions, clarifying that human inventors using AI tools can qualify as inventors if they made a "significant contribution" to the claimed invention. The guidance drew the line at AI operating autonomously; human-AI collaboration patents remain eligible. The guidance has significant implications for drug discovery, materials science, and software development sectors where AI is playing an increasing role in generating patentable innovations.
• Patent Quality Initiative and examination pendency: USPTO has maintained focus on reducing examination pendency (the time from application filing to first Office Action) and improving patent quality. Average total pendency was approximately 24–26 months as of 2025–2026. USPTO's Compact Prosecution and Interview Practice initiatives encourage earlier resolution of claim issues through applicant-examiner dialogue.
• Fee structure updates (2023): USPTO updated fee schedules effective January 2023, increasing most prosecution fees to reflect operating costs. Micro entity fees (80% reduction from standard) and small entity fees (60% reduction) were maintained. Fee increases affect continuation applications, claims in excess of standard counts, and appeal fees — which are particularly relevant for high-volume patent filers in pharmaceutical and technology sectors.
• Section 101 and patent eligibility uncertainty: The Supreme Court's Alice/Mayo framework for determining patent eligibility under 35 U.S.C. § 101 continues to create uncertainty, particularly for software, business method, and biotechnology patents. USPTO's 2019 Section 101 guidance attempted to clarify examination standards, but the underlying case law remains contested. Congress has repeatedly considered legislative reform to § 101 to restore eligibility for certain technology categories, without enacting a fix as of 2026.

Pending Action

35 U.S.C. § 101 patent eligibility reform remains the most significant pending legislative action affecting patent prosecution. The Patent Eligibility Restoration Act (PERA) — which would abrogate the Alice/Mayo framework and eliminate the judicial exceptions to § 101 — has been introduced in multiple Congresses and is actively being debated in the Senate Judiciary Committee's Intellectual Property Subcommittee. If enacted, PERA would require USPTO to issue new § 101 examination guidelines and would create substantial reexamination opportunities for previously rejected applications. Separately, USPTO's AI inventorship guidance from 2024 may require formal rulemaking to codify its "significant contribution" standard — watch the USPTO's regulatory agenda for a proposed rule addressing AI-assisted invention prosecution procedures. Fee schedule updates occur periodically; check the USPTO fee schedule on the agency's website for current amounts before filing.