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A defendant served with a patent infringement complaint typically has 21 days to respond under Fed. R. Civ. P. 12(a)(1)(A)(i), and the choice of forum, defenses, and timing is governed by the interaction of Rule 12, the patent venue statute at 28 U.S.C. § 1400(b), the local patent rules of the chosen district, and the one-year IPR clock under 35 U.S.C. § 315(b). Each path forecloses some defenses and preserves others; the first-month decisions are strategic, not procedural, and they shape the next two years of the litigation.

Keyhani LLC represents plaintiffs and defendants in patent infringement litigation and broader federal district court IP litigation in the District of New Jersey, the Southern and Eastern Districts of New York, and federal courts nationwide. The decisions a general counsel, CEO, or business owner has to make in the first 30 days of being sued for patent infringement — in the order they actually have to be made — are walked through below, with the governing federal rules and Supreme Court doctrine that constrain each step.

Do Not Communicate with the Patentee Directly

The single most damaging step a defendant’s business team can take in the first week of a patent dispute is calling, emailing, or meeting with the patentee or its counsel without litigation counsel involved. Statements made in those exchanges become exhibits. Casual concessions about how a product works, when it was launched, who designed it, or what the team knew about the asserted patent are routinely cited in willfulness briefing months later, where Halo Electronics, Inc. v. Pulse Electronics, Inc., 579 U.S. 93, 103–04 (2016) ties § 284 enhancement to a discretionary egregiousness standard informed by willfulness — Halo abolished the rigid Seagate test, but enhancement still requires conduct egregious enough to warrant the court’s discretion under § 284, with willfulness as the heartland of that inquiry.

The same rule applies to ignoring the lawsuit. A cease-and-desist letter or complaint cannot be set aside while the engineering team continues to ship the accused product without an internal review. Continued sales after notice, with no documented investigation, are precisely the facts plaintiffs use to argue willful infringement under the Halo standard and to seek attorney fees under Octane Fitness, LLC v. ICON Health & Fitness, Inc., 572 U.S. 545, 554 (2014) (totality-of-the-circumstances “exceptional case” standard under § 285). The two remedies operate independently: Halo‘s willfulness standard governs § 284 enhancement up to three times the damages found, while Octane‘s exceptional-case standard governs § 285 fee-shifting; willfulness alone does not automatically trigger § 285 fees, and a fee award does not depend on willfulness findings.

Preserve Documents and ESI Immediately

The duty to preserve evidence in federal civil litigation attaches when litigation is reasonably anticipated — not when the complaint is served. For a company that has received a cease-and-desist letter or a licensing demand identifying a specific patent, that duty has typically already attached. Routine document destruction policies, automated email purges, and chat-platform retention defaults must be suspended for the relevant custodians and systems on a documented basis.

Fed. R. Civ. P. 37(e) governs the consequences of getting this wrong. Under Rule 37(e), if electronically stored information (ESI) that should have been preserved is lost because a party “failed to take reasonable steps to preserve it,” and it cannot be restored or replaced through additional discovery, the court may order curative measures “no greater than necessary to cure the prejudice.” Where the court further finds that the party acted “with the intent to deprive another party of the information’s use in the litigation,” Rule 37(e)(2) authorizes adverse-inference instructions, dismissal, or default judgment.

Practically, the litigation hold in a patent case has to reach the people who would not normally see one: the founding engineers, departed employees with archived mailboxes, contract manufacturers, the marketing team that wrote the product launch deck, and the cloud-storage administrator who controls retention defaults on Google Workspace, Microsoft 365, Slack, GitHub, or whatever else the company runs. Source-code repositories, build histories, design files, and customer-facing documentation describing how the accused product works are all in scope.

Read the Patent and the Complaint Carefully

Once preservation is in place, the next step is substantive: get the asserted patent and the complaint in front of someone who can actually read them. The complaint will identify the asserted patent (or patents) by number, the specific claims asserted, and at least some of the accused products or product features. The patent itself, retrievable through Google Patents or USPTO Patent Center, contains the claims that define the scope of the alleged exclusive right, the specification that teaches what the invention is, and the prosecution history that may constrain how the claims can be read.

Two questions drive the early read. First, do the asserted claims, on their face, plausibly cover the accused product? Second, is there obvious prior art — a public product, a printed publication, an earlier patent — that predates the asserted patent’s priority date and arguably anticipates or renders obvious the claims under § 102 or § 103? An honest answer to those two questions, however preliminary, frames every later strategic decision. Indefiniteness defenses are governed by Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 901 (2014) (claim is indefinite if it fails to inform skilled artisans about the scope of the invention with reasonable certainty), and warrant their own column in the prior-art and claim-language read.

Software-method claims raise a third question early: is the patent vulnerable under Alice Corp. Pty. Ltd. v. CLS Bank International, 573 U.S. 208 (2014)? The two-step framework articulated in Alice — whether the claims are directed to a patent-ineligible abstract idea, and if so, whether they recite an inventive concept sufficient to transform the claim into a patent-eligible application — has produced a substantial body of motion-to-dismiss decisions invalidating software-method claims at the pleadings stage under § 101. A strong § 101 argument may justify a Rule 12(b)(6) motion before the answer is ever filed.

Evaluate Venue Under TC Heartland

Patent venue is narrower than general federal venue, and after TC Heartland it is meaningfully constrained. The patent venue statute, 28 U.S.C. § 1400(b), provides that any civil action for patent infringement may be brought in the judicial district where the defendant resides, or where the defendant has committed acts of infringement and has a regular and established place of business. In TC Heartland LLC v. Kraft Foods Grp. Brands LLC, 581 U.S. 258, 262 (2017), the Supreme Court held that “[a]s applied to domestic corporations, ‘reside[nce]’ in § 1400(b) refers only to the State of incorporation,” rejecting the broader corporate-residence definition in the general venue statute, 28 U.S.C. § 1391. TC Heartland‘s domestic-corporation rule does not extend to foreign defendants (governed by 28 U.S.C. § 1391(c)(3)) or to LLCs, partnerships, and individuals, each of which carries its own venue analysis.

The Federal Circuit then construed the “regular and established place of business” prong in In re Cray Inc., 871 F.3d 1355 (Fed. Cir. 2017) (requiring a physical, regular, established place of business that is the defendant’s place — employee home offices generally do not qualify). Together, TC Heartland and In re Cray mean a Delaware-incorporated company with all operations in Northern New Jersey is properly sued for patent infringement only in the District of Delaware or the District of New Jersey — not in the Eastern District of Texas, the Western District of Texas, or wherever the patentee finds convenient. A Rule 12(b)(3) motion to dismiss for improper venue, or a 28 U.S.C. § 1404(a) motion to transfer for convenience, is a routine first-month evaluation.

Defendant Profile	Proper Patent Venue	Authority
Domestic corporation, no other ties	State of incorporation only (resides prong)	TC Heartland, 581 U.S. 258 (2017); 28 U.S.C. § 1400(b)
Domestic corporation with physical office in district	State of incorporation, plus any district with regular and established place of business + acts of infringement	28 U.S.C. § 1400(b); In re Cray, 871 F.3d 1355 (Fed. Cir. 2017)
Foreign defendant	Any judicial district where the defendant is subject to personal jurisdiction; TC Heartland‘s residence rule is inapplicable	28 U.S.C. § 1391(c)(3); In re HTC Corp., 889 F.3d 1349 (Fed. Cir. 2018) (post-TC Heartland: alien defendants remain outside § 1400(b) and § 1391’s general venue limits)
Improper venue	Dismissal or transfer under 28 U.S.C. § 1406(a) / Rule 12(b)(3)	Fed. R. Civ. P. 12(b)(3); 28 U.S.C. § 1406(a)

The Decision Tree: Rule 12 Motion or Answer

The 21-day clock under Fed. R. Civ. P. 12(a)(1)(A)(i) can be addressed in three ways: serve an answer, file a Rule 12 motion, or stipulate to an extension. Rule 12(b) lists seven defenses that may be raised by motion before pleading: (1) lack of subject-matter jurisdiction, (2) lack of personal jurisdiction, (3) improper venue, (4) insufficient process, (5) insufficient service of process, (6) failure to state a claim upon which relief can be granted, and (7) failure to join a party under Rule 19. The defenses available against a patent complaint typically reduce to three on this list: improper venue under Rule 12(b)(3), failure to state a claim under Rule 12(b)(6) (often combined with a § 101 patent-eligibility argument), and, less commonly, lack of personal jurisdiction.

A Rule 12 motion does not stay the answer deadline indefinitely. Under Rule 12(a)(4), if the motion is denied or the court postpones disposition until trial, a responsive pleading is due within 14 days after notice of the court’s action, unless the court sets a different time. The choice between motion and answer is rarely binary. Filing a Rule 12(b)(6) motion arguing the asserted claims fail under Alice and § 101 can resolve the case at the pleadings stage in a clean software-patent posture. Filing a Rule 12(b)(3) motion to dismiss for improper venue, or a 28 U.S.C. § 1404(a) motion to transfer to a more convenient forum, can move the case from a forum the patentee selected to one closer to the defendant’s witnesses and documents. Answering immediately, with affirmative defenses and counterclaims for declaratory judgment of noninfringement and invalidity, can signal a willingness to litigate and reset settlement leverage.

Local Patent Rules in D.N.J., SDNY, and EDNY

The Federal Rules set the floor; the local patent rules of the chosen district structure the substantive workflow. In the District of New Jersey, L. Pat. R. 3.1 sets disclosure of asserted claims and infringement contentions at 14 days after the initial scheduling conference; L. Pat. R. 3.6 sets invalidity contentions at 45 days after service of the infringement contentions. L. Pat. R. 4.5(a) requires opening Markman briefs and supporting evidence not later than 45 days after the parties submit their joint claim construction and prehearing statement, with responding briefs due not later than 60 days after the opening submissions under L. Pat. R. 4.5(c) (the standard claim-construction track; design patent and other narrower-record postures use a 30-day responding window). The Southern and Eastern Districts of New York have adopted shared Local Patent Rules whose claim-construction briefing runs on a 30/30/7-day opening/response/reply sequence keyed to a Joint Disputed Claim Terms Chart.

The local-rule cadence matters in two ways. First, a defendant who has not internalized the disclosure deadlines will lose contention amendments to deadlines that ran while the team was still focused on the answer. Second, the rhythm of contentions, claim construction, and the Markman ruling under Markman v. Westview Instruments, Inc., 517 U.S. 370, 372 (1996) (claim construction is a question of law for the court), drives every meaningful settlement window in the case.

Evaluate the Validity Defenses Under Section 282

Validity defenses are the substantive core of most patent defenses. The defenses are codified by subsection at 35 U.S.C. § 282(b). The lead subsections are § 282(b)(1) for noninfringement, § 282(b)(2) for prior-art invalidity (anticipation under § 102, obviousness under § 103), and § 282(b)(3)(A) for any failure of § 112 (the written-description, enablement, and definiteness requirements). Read in full, the four lead subsections cover the universe of typical patent defenses.

§ 282(b)(1) covers “[n]oninfringement, absence of liability for infringement or unenforceability.” § 282(b)(2) reaches “[i]nvalidity of the patent or any claim in suit on any ground specified in part II [of this title] as a condition for patentability,” which incorporates anticipation under § 102 and obviousness under § 103. Courts have read § 282(b)(2) to incorporate § 101 patent-eligibility challenges as well, though the textual fit — whether § 101 is a “condition for patentability” — remains debated. The subsection supporting an indefiniteness defense is § 282(b)(3)(A): it covers “any requirement of § 112, except that the failure to disclose the best mode shall not be a basis on which any claim of a patent may be canceled or held invalid or otherwise unenforceable.” § 282(b)(3)(B) covers “any requirement of § 251” (reissue); and § 282(b)(4) preserves “[a]ny other fact or act made a defense by this title.”

Each ground has its own evidentiary apparatus. Anticipation under § 102 turns on prior public use, sale, publication, or patent — usually proved with public-record evidence assembled during invalidity contentions. Obviousness under § 103, the more common attack, applies the framework of KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 415 (2007), which rejected rigid application of the “teaching, suggestion, or motivation” test and instructed courts to apply an “expansive and flexible” obviousness inquiry. Indefiniteness under § 112(b) is governed by Nautilus, 572 U.S. 898, which held that a claim is indefinite if “its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.” In district court, an issued patent enjoys the presumption of validity under § 282(a), and an accused infringer must overcome it by clear and convincing evidence per Microsoft Corp. v. i4i Ltd. P’ship, 564 U.S. 91, 95 (2011).

Decide Whether to File an IPR Petition

IPR at the PTAB is a separate strategic forum that has to be evaluated — not deferred — in the first months of the case. 35 U.S.C. § 315(b) imposes a hard one-year time bar: an IPR “may not be instituted if the petition requesting the proceeding is filed more than 1 year after the date on which the petitioner, real party in interest, or privy of the petitioner is served with a complaint alleging infringement of the patent.” That clock starts on the day the complaint is served and runs for the petitioner, its real parties in interest, and its privies; voluntary dismissal of the underlying suit without prejudice does not reset the clock under Click-to-Call Technologies, LP v. Ingenio, Inc., 899 F.3d 1321 (Fed. Cir. 2018) (en banc as to footnote 3) (voluntary dismissal of underlying suit does not reset the § 315(b) clock). Under Thryv, Inc. v. Click-to-Call Technologies, LP, 590 U.S. 45 (2020), § 314(d) precludes appellate review of the Board’s § 315(b) timeliness determinations — statutory non-reviewability, not Article III jurisdictional vacatur, so the petitioner’s calendar must be right at filing.

A separate, often-overlooked bar at § 315(a)(1) forecloses IPR if the petitioner has previously filed a civil action challenging the validity of any claim of the patent. The classic trap is filing a declaratory-judgment action and then trying to file an IPR; the DJ filing forecloses the IPR even though § 315(a)(3) provides that an invalidity counterclaim “does not constitute a civil action challenging the validity of a claim of a patent for purposes of this subsection.” Joinder under § 315(c) is read narrowly: Facebook, Inc. v. Windy City Innovations, LLC, 973 F.3d 1321, 1336 (Fed. Cir. 2020) limits § 315(c) to joinder of a different party and forecloses same-party “issue joinder” — a petitioner cannot use § 315(c) to add itself as a party to its own already-instituted IPR, and cannot use joinder to add new claims or grounds (including time-barred ones) after the § 315(b) clock has run.

An IPR is a focused validity challenge limited to anticipation and obviousness grounds based on patents and printed publications under § 311(b). Filed strategically, an IPR can produce a stay of the district court action, a Final Written Decision (FWD) invalidating the asserted claims within 12 months of institution under § 316(a)(11), extendable up to 18 months for good cause, and broad estoppel under § 315(e) on grounds the petitioner “raised or reasonably could have raised” — the scope of which was clarified in Cal. Inst. of Tech. v. Broadcom Ltd., 25 F.4th 976, 990–91 (Fed. Cir. 2022) (overruling Shaw Indus. Grp., Inc. v. Automated Creel Sys., Inc., 817 F.3d 1293 (Fed. Cir. 2016)) on the instituted-vs-non-instituted-grounds question and confirming, as to the challenged claims, that the “reasonably could have raised” inquiry sweeps in grounds beyond those the Board instituted.

The discretionary-denial framework under Apple Inc. v. Fintiv, Inc., IPR2020-00019, Paper 11 (PTAB Mar. 20, 2020) (precedential), remains in force as the operative six-factor analysis. What changed is who decides and on what guidance: the February 28, 2025 rescission of the 2022 Vidal memo eliminated the prior bright-line safe harbors, and the October 17, 2025 Squires memorandum (effective October 20, 2025) placed institution decisions with the Director in consultation with at least three PTAB judges. Against that backdrop, a Sotera-style stipulation under Sotera Wireless, Inc. v. Masimo Corp., IPR2020-01019, Paper 12 (PTAB Dec. 1, 2020) (designated precedential as to § II.A Dec. 17, 2020) remains a strong factor against discretionary denial but is no longer a categorical safe harbor.

The decision tree is whether the strongest invalidity grounds are anticipation/obviousness on patents and publications (favoring IPR) or § 112 / § 101 / inequitable conduct (which stay in district court).

Plan for Damages and Injunctive Exposure

Damages exposure is the question business decision-makers ask first. Under 35 U.S.C. § 284, a patentee who proves infringement is entitled to “damages adequate to compensate for the infringement, but in no event less than a reasonable royalty for the use made of the invention by the infringer.” § 284 also permits the court to “increase the damages up to three times the amount found or assessed” — the willfulness enhancement that Halo tied to egregious misconduct under a discretionary standard. Attorney fees under § 285 are governed by Octane‘s totality-of-the-circumstances “exceptional case” standard and operate independently of willfulness; the § 284 and § 285 inquiries are separate.

Injunctive exposure is now narrower than it once was. Under eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388, 391 (2006), a permanent injunction in a patent case requires the plaintiff to demonstrate (1) “that it has suffered an irreparable injury,” (2) “that remedies available at law are inadequate to compensate for that injury,” (3) “that, considering the balance of hardships between the plaintiff and defendant, a remedy in equity is warranted,” and (4) “that the public interest would not be disserved by a permanent injunction.” eBay ended the near-automatic injunction practice that prevailed under earlier Federal Circuit precedent and reduced — though it did not eliminate — the leverage non-practicing entities (NPEs) can exert through injunction threats. Operating-company plaintiffs who actually compete with the defendant remain better positioned to satisfy the four-factor test than NPEs are.

Per-Side Perspective: Defendant vs. Patent Owner

Map the Litigation Timeline

A patent infringement lawsuit in federal district court typically runs 18 to 36 months from complaint to trial, with appellate review to the Federal Circuit thereafter. The variance is real: the District of Delaware moves faster than many forums, the Eastern and Western Districts of Texas have specific patent procedures, and the District of New Jersey and the Southern and Eastern Districts of New York operate under local patent rules that structure each phase on a defined schedule.

The high-level path runs through pleadings (months 1–3), infringement and invalidity contentions (months 3–6), claim-construction discovery and Markman briefing (months 6–12), fact discovery (months 6–15), expert discovery (months 12–18), summary judgment (months 15–20), and trial (months 20–30). An IPR filed in months 3–6, if instituted, often runs to a Final Written Decision in months 18–24 — sometimes ahead of trial, sometimes during it. Settlement windows open at every transition: after the answer, after Markman, after invalidity contentions are exchanged, and on the eve of summary judgment.

Cost Drivers in Patent Litigation

Patent litigation costs vary by case complexity, technology, forum, and the number of asserted patents and claims. Cost drivers that have outsized effects include the number of asserted claims that proceed to claim construction, the volume of source-code and ESI in discovery, the number of expert witnesses required (technical and damages), whether an IPR is filed in parallel, and whether the case proceeds to trial or resolves at summary judgment or in mediation. The American Intellectual Property Law Association’s biennial Report of the Economic Survey publishes per-case median cost ranges by amount-in-controversy bands, and the Lex Machina patent litigation analytics platform tracks forum-by-forum trial rates, time-to-trial, and outcome distributions; counsel typically use both data sources in early budgeting. To discuss budget and forum-specific cost expectations for a particular matter, contact Keyhani LLC.

Why Keyhani LLC for Patent Infringement Defense

Keyhani LLC represents plaintiffs and defendants in federal patent litigation in the District of New Jersey, the Southern and Eastern Districts of New York, and (pro hac vice) federal courts nationwide, and advises on parallel PTAB strategy and Federal Circuit appeals from PTAB decisions. The firm is an intellectual property litigation boutique handling defense-side and plaintiff-side patent matters from cease-and-desist response through Markman, summary judgment, trial, and appeal.

Darius Keyhani is admitted to the bars of the District of Columbia, New Jersey, the U.S. Court of Appeals for the Federal Circuit, the U.S. Supreme Court, and the Southern, Eastern, and Western Districts of New York, and holds an LL.M. from NYU School of Law. The firm regularly handles defense-side patent litigation from cease-and-desist response and complaint analysis through Markman, summary judgment, trial, and appeal — including venue and 28 U.S.C. § 1404(a) transfer practice, IPR-timing and parallel-PTAB advisory strategy, Federal Circuit appeals from PTAB decisions, and the § 282 validity defenses that drive substantive disposition of most patent cases.

Frequently Asked Questions About Being Sued for Patent Infringement

A Markman hearing is a federal pretrial proceeding at which the district judge construes the disputed terms of a patent’s claims as a matter of law. The name comes from Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996) (unanimous; claim construction is a question of law allocated to the judge), in which the Supreme Court held that claim construction is “exclusively within the province of the court.” Id. at 388–89. The judge’s constructions govern summary judgment and bind the jury’s infringement analysis at trial. Appellate review runs under Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015): de novo on the ultimate legal construction, clear-error on subsidiary fact-findings.

Keyhani LLC represents plaintiffs and defendants in patent infringement litigation and broader federal district court IP litigation in the District of New Jersey, the Southern and Eastern Districts of New York, and federal courts nationwide. The sections below explain what a Markman hearing is, how the governing Phillips methodology constrains claim construction, how Teva changed appellate review, and how the local patent rules in D.N.J., SDNY, and EDNY structure the process from disclosure through hearing.

This article is general information about U.S. patent claim-construction practice, not legal advice. Readers facing a specific Markman issue should consult counsel about the particulars of their case.

Why Judges, Not Juries, Decide Patent Claim Meaning

Before 1996, courts divided on whether claim construction was a factual question for juries or a legal question for judges. The Supreme Court resolved the debate in Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996). Justice Souter’s unanimous opinion proceeded in two complementary steps. First, the Seventh Amendment historical analysis: the Court found no established 18th-century jury practice for construing patent terms; the historical analogues did not control. Markman, 517 U.S. at 377–84. Second, functional considerations — judicial competence to parse technical documents and the uniform-interpretation interest in advancing the public-notice function of the patent system — confirmed the allocation rather than standing apart from the Seventh Amendment conclusion. Id. at 388–90. The Court held that “the construction of a patent, including terms of art within its claim, is exclusively within the province of the court.” Id. at 388–89.

That allocation of authority produced the hearing that now bears the case’s name. When the parties identify disputed claim terms, the district judge construes those terms before trial so that infringement and validity can be litigated against a fixed meaning of the claim language.

When Does the Markman Hearing Happen in a Patent Case?

There is no single federal deadline for the Markman hearing. Timing is set by the district judge’s scheduling order under Fed. R. Civ. P. 16 and by any local patent rules the district has adopted, which typically control where they exist. In many patent cases, the hearing occurs after claim-construction discovery and before later phases of expert discovery, although timing varies significantly by district and judge. Summary judgment motions frequently follow the claim-construction ruling, because the meaning the judge adopts often determines whether the accused product reads on the claim or whether a prior-art reference anticipates it.

The typical Markman workflow in federal patent cases proceeds through three defined stages.

How Does a Judge Construe a Disputed Claim Term?

The controlling methodology for claim construction comes from the Federal Circuit’s en banc decision in Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc; abrogating the dictionary-first approach of Texas Digital Systems). The court construes terms as a person of ordinary skill in the art (“POSITA”) would have understood them at the time of the invention — the POSITA is the lens through which the intrinsic record is read. Phillips established a hierarchy: the judge first looks to intrinsic evidence — the claim language itself, read in the context of the specification and the prosecution history — and only turns to extrinsic evidence, such as expert testimony and dictionaries, as a secondary source. Id. at 1314–19. Claim differentiation — the presumption that an independent claim is not limited to a feature that appears only in a dependent claim — often shapes construction when an independent claim is read against the added limitations of its dependents. See Phillips, 415 F.3d at 1314–15.

Within that hierarchy, the specification carries particular force. The en banc Phillips court reiterated that the specification is “the single best guide to the meaning of a disputed term.” Id. at 1315 (quoting Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996)). The prosecution history — the applicant’s and patent owner’s exchanges with the United States Patent and Trademark Office (USPTO) — lacks the specification’s clarity for ordinary claim-construction purposes, but it may be dispositive under the prosecution-disclaimer doctrine (also called disavowal) where the applicant or patent owner clearly and unmistakably disclaimed claim scope. The Federal Circuit extended that doctrine to statements made during inter partes review (IPR) in Aylus Networks, Inc. v. Apple Inc., 856 F.3d 1353, 1359–61 (Fed. Cir. 2017) (holding that a patent owner’s statements in an IPR preliminary response and post-institution response can support prosecution disclaimer in district-court litigation).

Phillips did not emerge from nowhere. The specification-primacy approach originated nine years earlier in Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576 (Fed. Cir. 1996). Vitronics stated that “in most situations, an analysis of the intrinsic evidence alone will resolve any ambiguity in a disputed claim term” and that “[i]n such circumstances, it is improper to rely on extrinsic evidence.” Id. at 1583. Phillips confirmed the Vitronics approach en banc but softened the absolute exclusion of extrinsic evidence, recognizing that expert testimony, dictionaries, and treatises may be consulted as a secondary source so long as the intrinsic record retains primacy. Phillips, 415 F.3d at 1317–19.

When Must a Judge Resolve a Claim-Term Dispute?

A district court has an affirmative duty to resolve genuine disputes over claim scope. In O2 Micro International Ltd. v. Beyond Innovation Technology Co., 521 F.3d 1351 (Fed. Cir. 2008), the Federal Circuit held that “when the parties present a fundamental dispute regarding the scope of a claim term, it is the court’s duty to resolve it.” Id. at 1362. A judge cannot punt a disputed term to the jury under a bare “plain and ordinary meaning” label when the parties have identified a real disagreement about what that meaning is.

O2 Micro does not require construction of every term a party lists. Courts routinely deny construction requests for terms the parties do not genuinely dispute on scope — or for terms where “plain and ordinary meaning” is itself the resolution of the dispute. The distinction matters at Markman briefing: a term is worth construing when the parties’ proposals diverge on claim scope in a way that affects infringement or validity, not merely because counsel would prefer a particular form of words.

Indefiniteness at the Claim-Construction Stage

Indefiniteness arguments under 35 U.S.C. § 112(b) are commonly raised alongside claim construction. Indefiniteness is a validity defense under 35 U.S.C. § 282(b)(3)(A), which more broadly preserves § 112 invalidity defenses (other than best-mode non-disclosure, which the AIA carved out). The Supreme Court set the current standard in Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014): a claim is indefinite if, read in light of the specification and the prosecution history, it “fail[s] to inform, with reasonable certainty, those skilled in the art about the scope of the invention.” Id. at 901.

In litigation, two recurring interactions between claim construction and indefiniteness are commonly observed. First, because the intrinsic record is the primary source under Phillips, the same evidence used to construe a term often answers the definiteness question — judges can and do resolve both in the same order. Second, where a term cannot be construed because the intrinsic record leaves it fatally ambiguous, the claim may be invalidated for indefiniteness rather than given a strained construction. A defendant who briefs indefiniteness as an alternative to a narrow construction often secures either outcome as a win.

Appellate Review After Teva v. Sandoz

From 1998 to 2015, the Federal Circuit reviewed claim construction de novo across the board under Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998) (en banc), which held that claim construction is “a purely legal question, subject to de novo review on appeal.” Id. at 1454. That pure-de-novo rule produced a famously high reversal rate and drove strategic appeals.

The Supreme Court modified Cybor — not overruled it — in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015). Writing for the Court, Justice Breyer held that while the Federal Circuit still reviews the ultimate claim construction de novo, it must review the district court’s subsidiary factual findings based on extrinsic evidence for clear error under Fed. R. Civ. P. 52(a)(6). “[T]o overturn the judge’s resolution of an underlying factual dispute,” the Court explained, “the Court of Appeals must find that the judge, in respect to those factual findings, has made a clear error.” Id. at 327. Construction based solely on the intrinsic record — the claim language, specification, and prosecution history — remains reviewed de novo. Id. at 331–32; see also Shire Dev., LLC v. Watson Pharms., Inc., 787 F.3d 1359, 1368 (Fed. Cir. 2015) (post-Teva Federal Circuit gloss confirming that where the district court relied solely on intrinsic evidence, claim construction is reviewed de novo).

The practical effect of Teva is that how a district judge resolves expert-testimony disputes — for example, disagreements among experts about what the POSITA would have understood a technical term to mean — is reviewed with deference. The ultimate legal conclusion on claim meaning remains a question the Federal Circuit decides afresh. A Markman strategy that relies heavily on extrinsic expert testimony now has more protection on appeal than it did pre-Teva; a strategy built on intrinsic evidence alone enjoys no more appellate deference than it did before.

Markman framework: allocation between judge and jury, plus appellate-review standards.

Issue	Allocation / Standard	Source
Allocation of claim construction (trial court)	Judge, as a matter of law	Markman, 517 U.S. at 388–89
Appellate review — ultimate construction of a disputed term	De novo	Teva, 574 U.S. at 331
Appellate review — subsidiary fact-findings based on extrinsic evidence (expert testimony)	Clear error	Teva, 574 U.S. at 327; Fed. R. Civ. P. 52(a)(6)
Appellate review — construction based solely on intrinsic evidence (claim, specification, prosecution history)	De novo	Teva, 574 U.S. at 331–32 (modifying Cybor, 138 F.3d at 1454); Shire, 787 F.3d at 1368

A note on forum: Teva’s clear-error standard for subsidiary fact-findings is the standard for district-court claim-construction appeals to the Federal Circuit under FRCP 52(a)(6). It does not apply to Patent Trial and Appeal Board (PTAB) appeals, which run through the Administrative Procedure Act (APA)’s substantial-evidence standard under 5 U.S.C. § 706(2)(E). A Markman hearing is, by definition, a district-court proceeding — so Teva’s clear-error rule is the operative appellate-review framework for Markman rulings.

Markman Practice in the District of New Jersey

For patent cases filed in the District of New Jersey, the claim-construction sequence is structured by the D.N.J. Local Patent Rules. Under D.N.J. Local Patent Rule 4.1, the parties begin by exchanging proposed terms for construction on a schedule tied to infringement and invalidity contentions. Rule 4.2 then calls for an exchange of preliminary proposed constructions, and Rule 4.3 requires the parties to meet and confer and submit a Joint Claim Construction and Prehearing Statement.

Claim-construction discovery must be completed within 30 days of the joint statement under Rule 4.4. The briefing sequence then follows in Rule 4.5:

1. L. Pat. R. 4.5(a) — opening briefs. Both sides file their opening Markman briefs contemporaneously (not in a plaintiff-opens / defendant-responds sequence), 45 days after the Joint Claim Construction and Prehearing Statement.
2. L. Pat. R. 4.5(b) — opening-declarant expert discovery. Expert discovery from opening-submission declarants closes within 30 days after the opening submissions.
3. L. Pat. R. 4.5(c) — responding submissions. Responding Markman submissions are due 60 days after the opening submissions, subject to the assigned judge’s individual rules.

Rule 4.6 then calls for counsel to confer and propose a hearing schedule within two weeks of the responding submissions. The result is a structured scheduling framework governed by Rule 16 and implemented through local patent rules, within which courts may allow expert declarations and technology tutorials depending on the complexity of the case and the practices of the assigned judge. Term-number caps (for example, limiting the parties to ten disputed terms for briefing) are typically imposed by the individual judge’s standing order rather than the Local Patent Rules themselves — practitioners should check the assigned judge’s rules early.

For New Jersey corporate defendants and out-of-state patent owners litigating in D.N.J., the practical consequence is that claim-construction strategy has to be locked in well before the Joint Claim Construction and Prehearing Statement, because the briefing schedule after that document is tight and unforgiving.

Strategic Considerations: Patent Owner vs. Accused Infringer

The same claim term often looks different from the two sides of the v. The patent owner usually wants a construction broad enough to cover the accused product but narrow enough to avoid invalidating prior art — the classic claim-construction tightrope. The accused infringer usually wants a construction narrow enough that the accused product falls outside the claim, or broad enough that the claim reads on prior art and falls to anticipation or obviousness.

How Markman Rulings Drive Summary Judgment

A claim-construction ruling is procedural in form but frequently dispositive in effect. Once the court adopts a construction for each disputed term, the parties can evaluate the infringement case against the accused product with the claim meaning fixed. A narrower construction often means the accused product falls outside the claim, supporting a defendant’s motion for summary judgment of noninfringement. A broader construction often exposes the claim to invalidating prior art, supporting a defendant’s invalidity motion or an IPR challenge.

That is why claim construction is better treated as a strategic exercise rather than a purely procedural one. The proposed constructions filed in the joint statement are not neutral; they are designed to position the claim for a summary-judgment outcome once the court rules. A Markman hearing that appears to resolve only the meaning of six technical terms can, in practice, shape the outcome of the entire case.

What Happens at the Markman Hearing Itself?

The format of a Markman hearing varies by judge and district. Some judges hold lengthy live hearings with technology tutorials, live expert witnesses, and oral argument on each disputed term. Others conduct the claim-construction exercise primarily on the papers, holding a brief hearing for argument or no hearing at all. The assigned judge’s individual rules and scheduling order determine whether live testimony is permitted at the hearing itself.

Common components of a live Markman hearing include:

The Stakes of Claim Construction

The doctrinal arc behind a Markman hearing runs from a unanimous Supreme Court allocation in Markman — claim construction belongs to the judge, not the jury — through the en banc Phillips hierarchy that ranks intrinsic evidence above extrinsic, to Teva’s split standard of appellate review that rewards a clean evidentiary record on subsidiary fact-findings. The strategic implication is consistent across every patent case: the proposed constructions filed in the joint statement are not neutral procedural placeholders. They are designed to position the claim for a summary-judgment outcome once the court rules — on infringement for the patent owner, on noninfringement or invalidity for the accused infringer. A Markman hearing that appears to resolve only the meaning of a handful of technical terms can, in practice, decide which side prevails on the merits.

Why Keyhani LLC for Markman Strategy

Keyhani LLC is an intellectual property litigation boutique with substantial federal IP litigation experience as lead counsel. The firm handles patent infringement cases from complaint through trial and appeal, including claim-construction briefing and Markman hearings in the District of New Jersey, the Southern and Eastern Districts of New York, and other federal district courts.

Darius Keyhani is admitted to the bars of the District of Columbia, New Jersey, the U.S. Court of Appeals for the Federal Circuit, the U.S. Supreme Court, and the Southern, Eastern, and Western Districts of New York, and holds an LL.M. from NYU School of Law. The firm handles both plaintiff and defense-side Markman work — including claim-construction strategy, expert selection and declaration drafting, joint claim-construction statements, opening and responsive Markman briefing, and hearing presentation — and approaches claim construction as the strategic exercise it is.

Frequently Asked Questions About Markman Hearings

The Patent Trial and Appeal Board (PTAB) is the administrative tribunal within the U.S. Patent and Trademark Office that adjudicates contested post-grant patent validity proceedings and ex parte appeals from examiner rejections. Created by the America Invents Act of 2011, Pub. L. No. 112-29, § 7, the Board is an executive-branch administrative tribunal within the USPTO, staffed by Administrative Patent Judges (APJs) sitting in three-judge panels under 35 U.S.C. § 6; the appellate path runs to the U.S. Court of Appeals for the Federal Circuit under 35 U.S.C. § 319 and § 141, with a 63-day filing window under 37 C.F.R. § 90.3.

How the Board Sits Inside the USPTO

The PTAB replaced the Board of Patent Appeals and Interferences in September 2012, when the AIA’s contested-proceedings provisions took effect. Its statutory authority appears at 35 U.S.C. § 6, which provides that the Board “shall consist of the Director, the Deputy Director, the Commissioner for Patents, the Commissioner for Trademarks, and the administrative patent judges.” 35 U.S.C. § 6(a). APJs are appointed by the Secretary of Commerce and decide cases in three-judge panels. Pre-Squires panel-assignment practice was that the same three-judge panel handled both institution and the merits trial; the October 2025 Squires regime changed this for the institution phase only, where the Director now decides whether to institute in consultation with at least three PTAB judges, while the merits panel that handles trial post-institution continues to be a separate three-judge APJ panel.

The Supreme Court resolved the constitutional question in Oil States Energy Services, LLC v. Greene’s Energy Group, LLC, 584 U.S. 325, 337 (2018) (IPR constitutional under Article III + Seventh Amendment), holding that IPR is a permissible exercise of the public-rights doctrine and does not violate Article III or the Seventh Amendment. The Director-appointment question was resolved in United States v. Arthrex, Inc., 594 U.S. 1, 23 (2021) (severability cure — Director Review), where the Court severed the unreviewable-decision aspect of the APJ scheme and required Director review of final written decisions; that severance is now codified at 37 C.F.R. § 42.75.

The Trial Vehicles

Proceeding	Authority	Who/When	Grounds	Standard
Inter Partes Review (IPR)	35 U.S.C. §§ 311–319	Anyone but the patent owner; available against any issued U.S. patent. For AIA first-inventor-to-file patents, § 311(c)(1) timing requires waiting until the later of 9 months from issuance or reissue, or termination of any instituted PGR; the § 311(c) timing window does not apply to pre-AIA patents	§ 102 / § 103 only, on patents and printed publications	Preponderance, § 316(e)
Post-Grant Review (PGR)	35 U.S.C. §§ 321–329	9-month window post-grant; AIA patents only	Any ground that could be raised under § 282(b)(2) or (3), generally including §§ 101, 102, 103, and most § 112 grounds (best mode excluded)	Preponderance, § 326(e)
Covered Business Method (CBM)	AIA § 18 (transitional)	Sunset September 16, 2020 — closed program	Any ground that could be raised under § 282(b)(2) or (3) for covered financial-services patents	Preponderance
Derivation	35 U.S.C. § 135	Within 1 year of first publication of derived claim	Inventor derived claimed invention from earlier inventor	Preponderance
Ex parte appeal	35 U.S.C. §§ 134, 141	Applicant from examiner final rejection	Any ground of rejection	Review of the prosecution record for examiner error (not de novo patentability)

In practice, IPR is the predominant trial vehicle. PGR remains rare because of the 9-month window, the broader estoppel scope under § 325(e), and the availability of § 101 and § 112 challenges in district court via Rule 12 motions and summary judgment.

Petition, Preliminary Response, and Institution

A petitioner files an IPR petition meeting the 35 U.S.C. § 312(a) particularity requirements, identifies all real parties in interest, and pays the filing fee. The patent owner has three months from the date of the notice indicating that the petition has been accorded a filing date to file a Patent Owner Preliminary Response (POPR) under 37 C.F.R. § 42.107(b) — note that the clock runs from the notice of accorded filing date, not from the date the petition was first filed. Word-count limits at this stage and throughout trial are governed by 37 C.F.R. § 42.24: the IPR petition (§ 42.24(a)(1)(i)), the POPR (§ 42.24(b)(1)), and the patent owner response (§ 42.24(b)(2)) are each capped at 14,000 words, while the petitioner reply to a patent owner response (§ 42.24(c)(1)) and the sur-reply (§ 42.24(c)(4)) are each capped at 5,600 words.

Under the Squires regime announced October 17, 2025 (clarified October 20, 2025), the Director — in consultation with at least three PTAB judges — decides IPR and PGR institution on a consolidated record at a single phase that addresses both the discretionary-denial framework and the merits in one decision rather than the two-stage bifurcated process used between February and October 2025. The Squires institution regime applies to IPR and PGR; ex parte appeals, derivation proceedings, and the expired CBM program are governed by their own pre-existing procedures. This regime succeeds two prior phases: the June 21, 2022 Vidal memo (which constrained Fintiv-based discretionary denials) was rescinded on February 28, 2025; the March 26, 2025 Interim Processes for PTAB Workload Management memorandum, authored by Acting Director Coke Morgan Stewart, then established a bifurcated discretionary-vs-merits process; and the Squires memo replaced that bifurcation in October 2025. On March 11, 2026, the USPTO added three further discretionary considerations: petitioner U.S. manufacturing investment, patent-owner U.S. manufacturing footprint, and small-business petitioner status.

The substantive discretionary framework remains Apple Inc. v. Fintiv, Inc., IPR2020-00019 (precedential — six-factor discretionary-denial framework), with Sotera Wireless, Inc. v. Masimo Corp., IPR2020-01019 (precedential as to § II.A — stipulation as a strong factor against discretionary denial) recognized as a meaningful factor under Fintiv factor 4. After the February 28, 2025 rescission of the 2022 Vidal memo, however, a Sotera-style stipulation is no longer a categorical safe harbor or pathway around Fintiv denial — it remains a weighty consideration but the bright-line shall-not-deny treatment is gone. Under § 314(a), the Director may decline to institute even where the petition shows a reasonable likelihood of prevailing on at least one challenged claim.

The One-Year Bar, the Civil-Action Bar, and Joinder

Two § 315 bars govern when an IPR can be filed at all. Under 35 U.S.C. § 315(b), an IPR petition is barred if filed more than one year after the petitioner, real party in interest, or privy is served with a complaint alleging infringement. The Federal Circuit clarified in Click-to-Call Technologies, LP v. Ingenio, Inc., 899 F.3d 1321 (Fed. Cir. 2018) (panel; en banc agreement on voluntary-dismissal rule in fn 3) that voluntary dismissal of the underlying district-court suit without prejudice does not reset the § 315(b) clock; that aspect of Click-to-Call survives even though the Supreme Court vacated and remanded with instructions to dismiss in Thryv, Inc. v. Click-to-Call Technologies, LP, 590 U.S. 45 (2020) (§ 314(d) precludes appellate review of § 315(b) timeliness determinations — statutory non-reviewability, not Article III jurisdictional vacatur). The footnote-3 holding on the voluntary-dismissal rule was a 10-2 vote, with Judges Dyk and Lourie dissenting and Judge Taranto concurring separately — not a unanimous en banc panel.

§ 315(a)(1) imposes a separate, often-overlooked bar: an IPR petition is barred if the petitioner has previously filed a civil action challenging the validity of any claim of the patent. The classic trap is filing a declaratory-judgment action and then trying to file an IPR; the DJ filing forecloses the IPR even though counterclaims of invalidity in a defensive posture do not. § 315(a)(2) further provides that an IPR filed before any subsequent DJ challenge by the petitioner stays the DJ action.

For joinder, § 315(c) is read narrowly. Facebook, Inc. v. Windy City Innovations, LLC, 973 F.3d 1321, 1336 (Fed. Cir. 2020) (limiting the joinder provision to different-party, same-issue joinder), held that § 315(c) authorizes joinder only of a different party to an existing IPR on the same issues — it does not authorize same-party “issue joinder” that would let a petitioner add new claims or grounds to its own pending IPR after the § 315(b) clock has run. The procedural timing rule for joinder motions appears at 37 C.F.R. § 42.122(b): a motion for joinder must be filed no later than one month after institution of the proceeding to be joined.

The Trial: Discovery, Motions, and Final Written Decision

After institution, the proceeding moves to a one-year statutory trial under 35 U.S.C. § 316(a)(11), which requires the final written decision to issue within one year of institution, extendable for up to six months for good cause. In the typical schedule, the patent owner’s response and any motion to amend under § 316(d) are due roughly three months after institution; petitioner’s reply roughly three months later; sur-reply, oral hearing, and final written decision follow within the statutory window.

Discovery is limited and scoped under 37 C.F.R. § 42.51: mandatory initial disclosures, routine discovery (cross-examination of declarants, inconsistent statements, information cited in papers), and additional discovery only on a showing of “interests of justice” — 37 C.F.R. § 42.51(b)(2) — under Garmin Int’l, Inc. v. Cuozzo Speed Techs. LLC, IPR2012-00001 (precedential as to discovery factors).

Claim construction at the PTAB follows the Phillips standard. The November 13, 2018 amendments to 37 C.F.R. § 42.100(b) replaced the broadest-reasonable-interpretation standard with the Phillips v. AWH Corp., 415 F.3d 1303, 1312–13 (Fed. Cir. 2005) (en banc) framework — the same standard a federal district court applies under Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996) (claim construction is question of law). On Federal Circuit appellate review, claim construction’s ultimate legal conclusions receive de novo review. PTAB factual findings — including subsidiary fact-findings on extrinsic evidence — are reviewed for substantial evidence under the Administrative Procedure Act, 5 U.S.C. § 706(2)(E), per Dickinson v. Zurko, 527 U.S. 150 (1999) (APA substantial-evidence review of PTO factual findings), and Knowles Electronics LLC v. Cirrus Logic, Inc., 883 F.3d 1358, 1362 (Fed. Cir. 2018) (substantial-evidence standard for PTAB fact-findings). Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318, 332 (2015) (modifying Cybor — FRCP 52(a)(6) clear-error review for district-court fact-findings on extrinsic evidence) applies by analogy for the deference owed to subsidiary fact-findings in district-court appeals, but the operative PTAB-appeal standard remains substantial evidence, not clear error; the Federal Circuit modified Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998) (en banc), in the district-court appellate context only.

Motion to Amend

Under § 316(d) and 37 C.F.R. § 42.121, the patent owner may move to amend by canceling claims or proposing reasonable substitute claims. The MTA framework evolved in three distinct stages: (1) the USPTO launched the Motion to Amend Pilot Program in March 2019 (84 Fed. Reg. 9497), creating optional procedural mechanisms (preliminary guidance and revised MTAs) without first codifying burden allocation; (2) the December 21, 2020 final rule (85 Fed. Reg. 82923, 82936, effective January 21, 2021) separately codified the burden of persuasion at 37 C.F.R. § 42.121(d) and § 42.221(d), placing the burden on the petitioner to prove unpatentability of the substitute claims by a preponderance — that 2020 rule did NOT implement the pilot; and (3) the September 18, 2024 final rule made the pilot procedural mechanisms permanent and added new subsections governing preliminary guidance and revised motions. The legal foundation comes from Aqua Products, Inc. v. Matal, 872 F.3d 1290 (Fed. Cir. 2017) (en banc plurality — fragmented decision signaling that the patent owner should not bear the burden on patentability of substitute claims), which the USPTO subsequently codified through the 2020 rulemaking.

Final Written Decision and SAS

The final written decision must address all challenged claims and all grounds raised in the petition. SAS Institute Inc. v. Iancu, 138 S. Ct. 1348, 1359–60 (2018) (no partial institution — all challenged claims and grounds), held that § 318(a) requires the Board to address every claim challenged in the petition once it institutes — partial institution is not permitted, and the regime is all challenged claims AND all grounds. The Office’s post-SAS guidance confirms that institution is on all grounds in the petition or no grounds at all.

Estoppel and the Caltech Lineage

35 U.S.C. § 315(e) bars a petitioner from later asserting in district court or the ITC any ground that it “raised or reasonably could have raised” — 35 U.S.C. § 315(e)(2) — in an IPR that reached final written decision. The scope of that estoppel evolved through three Federal Circuit decisions:

Case	Holding
Shaw Industries Group, Inc. v. Automated Creel Systems, Inc., 817 F.3d 1293 (Fed. Cir. 2016) (pre-Caltech narrow-estoppel rule, since overruled)	Estoppel did not reach grounds the Board declined to institute. Caltech overruled Shaw on the specific instituted-vs-non-instituted-grounds question; lower courts continue to wrestle with how far the “reasonably could have raised” (35 U.S.C. § 315(e)(1)) inquiry extends in particular fact patterns, so practitioners should treat the surviving “skilled searcher” question as fact-sensitive.
California Institute of Technology v. Broadcom Ltd., 25 F.4th 976, 990–91 (Fed. Cir. 2022)	See Caltech (overruling Shaw — § 315(e) reaches non-instituted grounds): estoppel reaches all grounds the petitioner reasonably could have raised under § 315(e), regardless of institution status. Post-SAS, partial institution was eliminated, so the Shaw carve-out on instituted-vs-non-instituted grounds has no remaining doctrinal foundation, although the broader “reasonably could have raised” (25 F.4th at 990) inquiry remains fact-sensitive in lower courts.
Ironburg Inventions Ltd. v. Valve Corp., 64 F.4th 1274, 1295–98 (Fed. Cir. 2023) (allocating to the patent owner the burden of identifying grounds a skilled searcher conducting a diligent search reasonably could have located)	The patent owner asserting § 315(e) estoppel bears the burden of identifying grounds the petitioner reasonably could have located.

The interaction between the PTAB’s preponderance standard and the Microsoft Corp. v. i4i framework (establishing the clear-and-convincing evidence standard for invalidity defenses raised in district-court litigation) is the strategic heart of IPR practice. At the PTAB, validity is decided by preponderance of the evidence under § 316(e). In district court, an issued patent enjoys the presumption of validity under 35 U.S.C. § 282, and an accused infringer must overcome it by clear and convincing evidence per Microsoft Corp. v. i4i, 564 U.S. at 95 (clear-and-convincing evidence standard for invalidity). Because of that asymmetry, accused infringers often prefer the PTAB on art they can win on; once the final written decision issues, the § 315(e) estoppel triggers for any ground that the petitioner “raised or reasonably could have raised” under 35 U.S.C. § 315(e)(2).

Settlement, Termination, and the Director’s Discretion

Under 35 U.S.C. § 317, parties may file a joint settlement and request termination of the IPR. The Board may terminate the proceeding as to the settling parties and continue against any non-settling petitioners. Where settlement comes before institution, termination is the default; post-institution, the Board has discretion to issue a final written decision on the merits notwithstanding settlement, particularly where the record is closed. A settlement agreement filed under § 317(b) is treated as business confidential information and “shall be kept separate from the file of the involved patents,” 35 U.S.C. § 317(b), available only to Federal Government agencies on written request, or to any other person on a showing of good cause.

Director Review

After Arthrex, the Director has authority to review final written decisions sua sponte or on a party request. The current rule is at 37 C.F.R. § 42.75, as amended by the final rule at 89 Fed. Reg. 79744, 79751 (Oct. 1, 2024), which formalized the Director Review process the Office had typically operated by interim procedure since 2021. Director Review is discretionary and is granted in only a small fraction of cases; rehearing under 37 C.F.R. § 42.71 is the more commonly used mechanism for procedural error or overlooked argument.

Federal Circuit Appeal

A party adverse to a final written decision may appeal to the Federal Circuit under 35 U.S.C. § 319 and 28 U.S.C. § 1295(a)(4)(A) — the exclusive appellate path, though appeal itself is optional. The notice of appeal is filed within 63 days of the final written decision under 37 C.F.R. § 90.3(a)(1); when timely rehearing is sought, § 90.3(b)(1) resets the clock to 63 days after action on the rehearing request. Extensions are governed by § 90.3(c)(1), which requires good cause (pre-expiration) or excusable neglect (post-expiration). Institution decisions remain non-appealable under 35 U.S.C. § 314(d), as construed in Cuozzo Speed Technologies, LLC v. Lee, 579 U.S. 261, 273 (2016) (sustaining the statutory bar on judicial review of institution decisions), and reaffirmed in Thryv.

The standard of review at the Federal Circuit follows the usual administrative-law pattern: legal conclusions are reviewed de novo, factual findings under the Administrative Procedure Act’s substantial-evidence test, and discretionary determinations for abuse of discretion. Standing to appeal a PTAB loss is itself a threshold question — see Phigenix and JTEKT, above.

Procedural Recap — Key Clocks at a Glance

Frequently Asked Questions