PTAB vs. District Court: Where to Challenge a Patent’s Validity

Sources: 35 U.S.C. § 282, § 311, § 314, § 315, § 316, § 321, § 141(c); 28 U.S.C. § 1295(a)(1), § 1914(a), § 2201(a); district court miscellaneous fee schedule; 37 C.F.R. § 42.15, § 42.51, § 42.100(b), § 42.102; MPEP § 2212; Fed. R. Civ. P. 26(b)(1); Microsoft Corp. v. i4i, 564 U.S. 91 (2011). Each row is explained below.

"A patent shall be presumed valid," and "the burden of establishing invalidity ... shall rest on the party asserting such invalidity" (35 U.S.C. § 282(a)). In Microsoft Corp. v. i4i (2011), the Supreme Court held that "Section 282 requires an invalidity defense to be proved by clear and convincing evidence." The Court added that when the USPTO did not have all material facts before it, "its considered judgment may lose significant force," and a jury may be instructed to consider whether the evidence before it is materially new.

At the PTAB, "the petitioner shall have the burden of proving a proposition of unpatentability by a preponderance of the evidence" (§§ 316(e), 326(e)). The Supreme Court drew the contrast in Cuozzo Speed Technologies v. Lee (2016): "In inter partes review, the challenger (or the Patent Office) must establish unpatentability ‘by a preponderance of the evidence’; in district court, a challenger must prove invalidity by ‘clear and convincing evidence.’"

That is why a claim can survive in court and still be cancelled at the USPTO on the same art. The USPTO says so in its own manual: a court’s final decision upholding a claim "does not necessarily mean that no new question is present. This is true because of the different standards of proof employed by the district courts and the Office," while a final holding of invalidity, after all appeals, is controlling on the Office (MPEP §§ 2242, 2286). Since September 16, 2025, if the Board reaches a different finding or conclusion from an earlier post-issuance adjudication by a court, the ITC or the USPTO of the same or substantially similar claims, it must explain why, in more detail where the same or substantially the same evidence or arguments are relied on.

Sources: 35 U.S.C. § 282(a), § 316(e); Microsoft Corp. v. i4i Limited Partnership, 564 U.S. 91 (2011); Cuozzo Speed Technologies, LLC v. Lee, 579 U.S. 261 (2016); MPEP §§ 2242, 2286; PTAB consideration of prior findings of fact and conclusions of law (Sept. 16, 2025).

In court, the defenses include noninfringement and unenforceability, invalidity on any condition for patentability in Part II of the Patent Act, and failure to meet § 112 (except best mode) or § 251 (§ 282(b)). That covers eligibility (§ 101), anticipation and obviousness over any prior art, including prior sales, public uses and products, and written description, enablement and definiteness.

At the PTAB, an IPR is limited to § 102 and § 103 "on the basis of prior art consisting of patents or printed publications" (§ 311(b)). A PGR can raise any § 282(b)(2) or (3) ground (§ 321(b)), but the petition must be filed within nine months of grant or reissue (identical or narrower reissue claims keep the original deadline), and only against patents under the first-inventor-to-file system. So once that window has closed without a PGR, a new PTAB challenge can raise only the printed-art half of the invalidity case, and eligibility, § 112 and prior uses and sales stay in court. The comparison of the two PTAB trials is in IPR vs. PGR.

Sources: 35 U.S.C. § 282(b), § 311(b), § 321, § 325(f).

• The one-year bar. An IPR may not be instituted if the petition is filed more than one year after the petitioner, its real party in interest or privy was served with a complaint alleging infringement of the patent, though the limit does not apply to a request for joinder (§ 315(b)). Whether the bar applies is decided by the USPTO and cannot be appealed (Thryv v. Click-to-Call, 2020).
• Do not sue first. If you or your real party in interest file a civil action challenging validity before petitioning, no IPR or PGR may be instituted (§§ 315(a)(1), 325(a)(1)); if either of you files it on or after the petition date, it is automatically stayed until the patent owner moves to lift the stay or files an infringement action or counterclaim against you or your real party in interest, or you or your real party in interest move to dismiss it (§§ 315(a)(2), 325(a)(2)). An invalidity counterclaim in the patent owner’s suit does not count (§§ 315(a)(3), 325(a)(3)).
• The PTAB clock. The patent owner has three months to file a preliminary response (37 C.F.R. § 42.107(b)); the institution decision follows within three months (§ 314(b)); a final written decision is due one year after institution, extendable by up to six months (§ 316(a)(11)). Those deadlines allow up to about 18 months from the filing-date notice to a final written decision, or about 24 with the full good-cause extension; joinder can change the schedule.
• The court clock. The court sets its own schedule. Under the PTAB’s Fintiv factors, an earlier trial date in the parallel case weighs toward denying institution.

Sources: 35 U.S.C. § 314(b), § 315(a)-(b), § 316(a)(11), § 325(a); 37 C.F.R. § 42.107; Thryv, Inc. v. Click-to-Call Technologies, LP, 590 U.S. 45 (2020); Apple Inc. v. Fintiv, Inc., IPR2020-00019, Paper 11 (PTAB Mar. 20, 2020) (precedential).

Institution is never guaranteed: the statute says the Director "may not" institute unless the threshold is met, not that the Director must institute when it is (§ 314(a)), and the decision "shall be final and nonappealable" (§ 314(d)). How that discretion is used with parallel litigation has changed repeatedly. As of October 15, 2026:

1. Fintiv is restored. The USPTO rescinded its June 2022 memorandum limiting Fintiv on February 28, 2025, restoring the Board’s precedential Fintiv and Sotera decisions. Fintiv’s factors are: whether the court granted or is likely to grant a stay; how close the court’s trial date is to the Board’s deadline; investment in the parallel case; overlap of issues; whether the petitioner is the defendant; and other circumstances, including the merits. A March 24, 2025 memorandum applies Fintiv to parallel ITC investigations too, treats a Sotera stipulation (not pursuing in court any ground raised or reasonably raisable in the IPR) as "highly relevant, but will not be dispositive by itself," lets the parties use median time-to-trial statistics, and says compelling merits alone are not dispositive.
2. The Director decides. Since March 26, 2025, the patent owner may file a separate brief requesting discretionary denial, and since October 20, 2025 the Director, with at least three PTAB judges, decides institution in IPRs and PGRs, usually by summary notice, and may refer a decision that needs detailed treatment to PTAB judges. Considerations include earlier decisions on the same claims, the strength of the challenge, reliance on expert testimony and "settled expectations of the parties, such as the length of time the claims have been in force."
3. U.S. manufacturing (March 11, 2026). The Director considers whether products accused in the parallel case are made in the United States, whether the patent owner’s competing products are, and whether the petitioner is a small business sued on the patent.
4. A proposed rule, not yet final. The USPTO proposed on October 17, 2025 (RIN 0651-AD89) to generally bar instituting or maintaining an IPR: unless the petitioner stipulates not to raise § 102 or § 103 invalidity in any other proceeding; where a district court trial, ITC determination or another final written decision on the claim is more likely than not to come before the IPR’s deadline; or where a claim was upheld in specified earlier rulings. A panel could refer extraordinary cases to the Director, who could institute personally. No final rule had been published in the Federal Register as of October 15, 2026.

Stays are the court’s call. A district court decides whether to pause the case for an IPR, and whether it has done so, or is likely to, is the first Fintiv factor.

Sources: 35 U.S.C. § 314; Apple Inc. v. Fintiv, Inc., IPR2020-00019, Paper 11 (PTAB Mar. 20, 2020) (precedential); Guidance on the rescission of the 2022 interim procedure (Mar. 24, 2025); Interim Processes for PTAB Workload Management (Mar. 26, 2025); Interim Director Discretionary Process; Director Institution of AIA Trial Proceedings (Oct. 17, 2025); U.S. Manufacturing and Small Business Use of AIA Proceedings (Mar. 11, 2026); Revision to Rules of Practice Before the PTAB, 90 FR 48335 (proposed Oct. 17, 2025).

If an IPR or PGR ends in a final written decision on a claim, the petitioner (unless its part of the review was terminated by settlement), its real party in interest and its privies "may not assert either in a civil action ... or in a proceeding before the International Trade Commission ... that the claim is invalid on any ground that the petitioner raised or reasonably could have raised" during the review (§§ 315(e)(2), 325(e)(2)).

• Reach. The Federal Circuit applies estoppel "not just to claims and grounds asserted in the petition and instituted for consideration by the Board, but to all claims and grounds not in the IPR but which reasonably could have been included in the petition" (California Institute of Technology v. Broadcom, 2022). Under § 315(e) it attaches to a claim that reached a final written decision.
• Limit. IPR estoppel "does not preclude a petitioner from asserting the same prior art raised in an IPR in district court"; it bars grounds that the claimed invention was patented or described in a printed publication. Grounds an IPR cannot hear, that the invention was known or used by others, on sale or in public use, survive even where the same patents or publications serve as evidence (Ingenico v. IOENGINE, 2025).
• Timing. Estoppel attaches only when the review "results in a final written decision" (§ 315(e)). A denied petition or a trial ended by settlement before the Office decides the merits creates none (§ 317(a)).
• Stipulations. A Sotera stipulation gives up those court grounds earlier than the statute does: if review is instituted, the petitioner will not pursue in court any ground raised or that reasonably could have been raised, without waiting for a final written decision. The USPTO treats such a stipulation as highly relevant to institution, though not dispositive by itself.

Sources: 35 U.S.C. § 315(e), § 317, § 325(e); California Institute of Technology v. Broadcom Ltd., 25 F.4th 976 (Fed. Cir. 2022); Ingenico Inc. v. IOENGINE, LLC, No. 2023-1367 (Fed. Cir. May 7, 2025); Guidance on the rescission of the 2022 interim procedure (Mar. 24, 2025).

• Discovery. In IPR, discovery is limited to depositions of witnesses who submit declarations and "what is otherwise necessary in the interest of justice" (§ 316(a)(5)); in PGR, to evidence directly related to the parties’ factual assertions (§ 326(a)(5)). In court, parties may obtain discovery of "any nonprivileged matter that is relevant to any party’s claim or defense and proportional to the needs of the case" (Fed. R. Civ. P. 26(b)(1)).
• Claim construction. Since 2018 the PTAB construes claims under the same standard used in a civil action, so the two forums now ask the same question; a prior court construction timely made of record will be considered (37 C.F.R. §§ 42.100(b), 42.200(b)).
• Amendment. At the PTAB the patent owner may move to amend, cancelling claims or proposing a reasonable number of narrower substitute claims (§ 316(d)); substitute claims added by the certificate have the same effect as reissued claims under § 252 for those who made, purchased, used or imported what they cover in the United States, or substantially prepared to, before the certificate (§ 318(c)). Amendment happens through the USPTO, whose certificate then adds the new claims to the patent (§ 318(b)).
• Government fees. An IPR costs $51,875 in USPTO fees for up to 20 claims and a PGR $59,375, with no small-entity discount. Filing a civil action costs $405 ($350 under 28 U.S.C. § 1914(a) plus a $55 administrative fee). These are government fees only; our official sources do not quantify attorney and expert fees in either forum.

Sources: 35 U.S.C. § 316, § 318(c); Fed. R. Civ. P. 26(b)(1); 37 C.F.R. § 42.15, § 42.100; USPTO fee schedule; 28 U.S.C. § 1914(a); district court miscellaneous fee schedule.

• Within the USPTO. A party may ask the Director to review an institution decision or a final written decision (37 C.F.R. § 42.75). In United States v. Arthrex (2021), the controlling opinion on remedy concluded that the Director "may review final PTAB decisions and, upon review, may issue decisions himself on behalf of the Board." Follow these decisions on our Director Review topic page.
• To the Federal Circuit. A party dissatisfied with a final written decision may appeal only to the Federal Circuit (35 U.S.C. § 141(c)), which also has exclusive jurisdiction over appeals from final district court decisions in actions arising under the patent laws or with a compulsory patent counterclaim (28 U.S.C. § 1295(a)(1)). A losing PTAB petitioner must show Article III standing to appeal; Consumer Watchdog v. WARF (Fed. Cir. 2014) dismissed an appeal by a challenger without an injury in fact.
• Article III and jury challenges rejected. Oil States v. Greene’s Energy (2018) held that IPR does not violate Article III or the Seventh Amendment, a holding the Court called narrow.

The Federal Circuit’s opinions in these appeals are summarized on our Federal Circuit topic page, and the hub for appeals is Federal Circuit.

Sources: 37 C.F.R. § 42.75; United States v. Arthrex, Inc., 594 U.S. 1 (2021); 35 U.S.C. § 141(c); 28 U.S.C. § 1295(a)(1); Consumer Watchdog v. Wisconsin Alumni Research Foundation, 753 F.3d 1258 (Fed. Cir. 2014); Oil States Energy Services, LLC v. Greene’s Energy Group, LLC, 584 U.S. 325 (2018).

• The PTAB favors a challenger whose best case is prior patents and publications, who would rather argue to patent judges than to a jury, and who can file well within the one-year bar, early enough that the court’s trial date does not overtake the Board’s schedule. The lower standard of proof and the chance to force amendments are the draw.
• Court favors a challenger whose case rests on eligibility, § 112, prior products, sales or public uses, or who wants to keep every theory without estoppel, accepting the clear-and-convincing standard and a jury.
• Pursuing both at once is now harder: under the Director’s process, an advanced parallel case, claims long in force or earlier rulings on the same claims weigh against institution, and a broad stipulation may be the price of getting in. Weigh what an estoppel would take off the table in court before filing.

Track how institution is going on our PTAB dashboard, read the latest discretionary denial decisions, obviousness and claim construction rulings, and see the district court hub and the PTAB hub. Reexamination, the other USPTO route, is compared in IPR vs. ex parte reexamination.

Sources: 35 U.S.C. § 282, § 311(b), § 315, § 316(e); Interim Processes for PTAB Workload Management (Mar. 26, 2025); Director Institution of AIA Trial Proceedings (Oct. 17, 2025). Which forum fits is our own view, not legal advice.