Guides · Patent Litigation

PTAB Proceedings and Parallel Litigation

An accused infringer can ask the Patent Office to cancel patent claims through inter partes review or post-grant review.

Published October 20, 2026 · Last reviewed October 20, 2026Law checked through October 20, 2026

In Short

An accused infringer can ask the Patent Office to cancel patent claims through inter partes review or post-grant review. These proceedings use a lower standard of proof than court and are decided by technically trained judges. Since 2025, however, the Patent Office has denied many petitions on discretionary grounds, the Director now decides every institution request personally, and a rule that would further restrict review is awaiting final approval. Anyone sued on a patent should plan for the possibility that review will not be available.

Common situations.

A company sued in Marshall wants to know whether a Patent Office challenge is worth filing.
A petition is denied without explanation, and the petitioner asks whether it can appeal.
A patent owner asks whether the court will pause the case while the Patent Office reviews the patent.

The proceedings.

	Inter partes review (IPR)	Post-grant review (PGR)	Ex parte reexamination
When	After nine months from grant, and within one year after being served with an infringement complaint (35 U.S.C. §§ 311(c), 315(b))	Within nine months after grant (§ 321(c))	Any time during the patent's enforceability
Grounds	Anticipation and obviousness, based only on patents and printed publications (§ 311(b))	Any ground of invalidity (§ 321(b))	Substantial new question of patentability based on patents and printed publications (§§ 302, 303)
Who takes part	Petitioner and patent owner, through trial	Petitioner and patent owner, through trial	Requester files; examination proceeds between the Office and the patent owner
Standard	Preponderance of the evidence (§ 316(e))	Preponderance (§ 326(e))	Examiner review
Estoppel	Yes, after a final written decision (§ 315(e))	Yes (§ 325(e))	No
Office fees	$23,750 request fee and $28,125 post-institution fee, for up to 20 claims (37 C.F.R. § 42.15(a))	$25,000 and $34,375 (§ 42.15(b))	Set by fee schedule

How an IPR unfolds.

Petition. The petitioner identifies the claims, the prior art, and the grounds, with expert declarations, and must name all real parties in interest.
Patent owner's preliminary response. Due about three months after notice of the petition. Since 2025, the parties also file separate briefs on discretionary denial.
Institution. A decision is due within three months after the preliminary response (§ 314(b)). The petitioner must show a reasonable likelihood of prevailing on at least one claim (§ 314(a)), but the Office may deny review even if that standard is met.
Trial. If review is instituted, a three-judge panel oversees limited discovery, briefing, and an oral hearing. The patent owner may move to amend its claims.
Final written decision. Due within one year after institution, extendable by six months for good cause (§ 316(a)(11)). Either party may ask the Director to review the decision (United States v. Arthrex, Inc., 594 U.S. 1 (2021)).
Appeal. Either party may appeal a final written decision to the Federal Circuit (§ 319).

Discretionary denial since 2025.

The Patent Office has always had discretion to deny institution, but its use of that discretion changed sharply beginning in 2025:

Parallel litigation. The Office considers whether a court or the ITC is likely to decide validity first, along with the stage of the case and overlap of issues (Apple Inc. v. Fintiv, Inc., IPR2020-00019, Paper 11 (PTAB Mar. 20, 2020) (precedential)). In February 2025, the Office withdrew a 2022 policy under which a petitioner could avoid this kind of denial by stipulating not to pursue the same grounds in court. Stipulations remain relevant but are not decisive.
Separate discretionary briefing. Under interim processes announced March 26, 2025, discretionary issues are briefed and decided separately from the merits.
"Settled expectations." Also in 2025, the Office began denying review of patents that had been in force for several years, reasoning that their owners had settled expectations in their validity.
Director decides institution. Effective October 20, 2025, the Director, consulting a small group of administrative patent judges, decides whether to institute every IPR and PGR, usually by a short summary notice without a written explanation.
Manufacturing and small business factors. Guidance issued March 11, 2026 adds whether the accused products or the patent owner's products are made in the United States, and whether the petitioner is a small business that has been sued.

Can denials be challenged?

Institution decisions are "final and nonappealable" (§ 314(d)). The Federal Circuit has denied mandamus petitions challenging the new policies (In re Motorola Sols., Inc., No. 2025-134 (Fed. Cir. Nov. 6, 2025)). The Supreme Court declined to review a challenge to the settled-expectations policy on October 19, 2026 (Google LLC v. VirtaMove, Corp., No. 25-1230, cert. denied).

The pending rule.

In October 2025 the Patent Office proposed rules (90 Fed. Reg. 48335) that would, among other things:

require petitioners to stipulate that they will not pursue anticipation or obviousness challenges in other forums;
bar review of claims already upheld against those challenges in court, at the ITC, or at the Patent Office; and
bar review when a court or the ITC is likely to decide validity before the Board would.

The Office received more than 11,000 comments. A final rule was sent to the Office of Information and Regulatory Affairs on July 22, 2026, and as of this update had not been published. This page will be updated when it is.

Coordinating with the court case.

Timing. The one-year deadline under § 315(b) runs from service of the complaint, not from when the defendant learns which claims matter. Defendants often must file before infringement contentions are final.
Stays. Courts weigh the stage of the case, whether review will simplify the issues, and prejudice to the patent owner. Many Texas judges deny stays requested before the Office decides whether to institute review.
Estoppel. A petitioner that reaches a final written decision cannot raise in court any patent-or-publication ground it raised or reasonably could have raised. See Burdens and Standards of Proof.
Claim construction. Statements a patent owner makes to defend its claims can narrow them in court. See Claim Construction (Markman).
Ex parte reexamination as an alternative. With IPR harder to obtain, more accused infringers are requesting reexamination. Since April 2026, patent owners may file a paper before the Office decides whether to order reexamination.

Sources.

35 U.S.C. §§ 302, 303, 311-319, 321-329.
37 C.F.R. § 42.15.
United States v. Arthrex, Inc., 594 U.S. 1 (2021).
Apple Inc. v. Fintiv, Inc., IPR2020-00019, Paper 11 (PTAB Mar. 20, 2020) (precedential).
USPTO, Interim Processes for PTAB Workload Management (Mar. 26, 2025).
USPTO, Director Institution of AIA Trial Proceedings (memorandum, Oct. 17, 2025; effective Oct. 20, 2025).
USPTO, guidance on discretionary denial factors (Mar. 11, 2026).
Revision to Rules of Practice Before the Patent Trial and Appeal Board, 90 Fed. Reg. 48335 (proposed Oct. 17, 2025); final rule received for review July 22, 2026 (RIN 0651-AD89).
In re Motorola Sols., Inc., No. 2025-134 (Fed. Cir. Nov. 6, 2025).
Google LLC v. VirtaMove, Corp., No. 25-1230 (U.S. cert. denied Oct. 19, 2026).

This guide is general information, not legal advice. Law checked through October 20, 2026. See the Disclaimer.