If you have been served with an infringement complaint, hit with an IPR petition, or are weighing your options after a competitor’s product launch, time matters. Inter Partes Review offers a faster path than district court proceedings to address patent validity, and it operates under rigid statutory deadlines that penalize delay. This overview explains how the process works at the Patent Trial and Appeal Board, what factors shape strategy, and when filing or responding may make practical sense for your business.
What Is Inter Partes Review? The Short Version
Congress created the Inter Partes Review in the America Invents Act, and it took effect on September 16, 2012. The procedure was designed to provide companies with a faster, lower-cost alternative to challenging validity in federal court.
- What it is: An administrative trial at the U.S. Patent and Trademark Office that may cancel claims of an issued patent.
- Who can file: Any third party who is not the patent owner.
- What it tests: Only anticipation (35 U.S.C. § 102) or obviousness (35 U.S.C. § 103).
- Burden of proof: Preponderance of the evidence.
- Where it lives: The Patent Trial and Appeal Board (PTAB), inside the USPTO.
What an IPR Actually Does
An IPR is a narrow tool. The petition asks the PTAB to cancel specific claims of a granted patent, and the only ammunition allowed is prior art patents and printed publications (older patents, published applications, journal articles, conference papers, and similar published documents). Invalidity theories that work in federal court, such as written description failures under § 112 or inventorship disputes, are off the table inside an IPR except in narrow claim construction contexts.
The proof burden at the PTAB is lower than in court, too. A petitioner need only show that cancellation is more likely than not. In federal litigation, that same petitioner would need clear and convincing evidence to overcome the statutory presumption of validity, which continues to apply in district court even when an IPR is pending.
Why Companies Choose IPR Over the District Court
IPR draws filings for a combination of practical reasons. The procedure may resolve validity faster than court litigation, since the PTAB is generally required to issue a final written decision within 12 months of instituting trial, subject to limited extensions and procedural exceptions. Discovery is narrower than in federal court, motion practice is capped, and there is no jury, which tends to keep costs more predictable than in full district-court invalidity proceedings. Many Administrative Patent Judges (APJs) hold technical or scientific degrees, which can influence how complex technologies are evaluated, although subject-matter expertise matching the patent at issue is not guaranteed.
Those benefits come with real trade-offs in estoppel and coordination with district court litigation. We cover those in the strategy section below.
The IPR Process Timeline at the PTAB
The statutory clock drives every stage of the procedure. Missing a deadline ends the case, so the calendar shapes strategy as much as the prior art does.
Filing the Petition and the One-Year Bar
Only a third party can file. The patent owner cannot, and the petition window has two boundaries:
- Earliest filing date: Nine months after patent grant, or after any post-grant review terminates, whichever is later.
- Latest filing date: Twelve months after the petitioner is served with a complaint for patent infringement, under 35 U.S.C. § 315(b).
The one-year bar is the hard stop most petitioners face. If you are served with a patent infringement claim in March, your petition must reach the PTAB before that same date the following year.
The one-year bar does not apply to a petition filed with a motion for joinder under § 315(c), though joinder itself remains discretionary and the PTAB has repeatedly denied joinder requests, including ones aimed at “me-too” or copycat petitions, where it found joinder would not serve the interests of justice.
What a Complete Petition Must Include
A petition that meets statutory requirements typically covers several required components:
- A list of every challenged claim and the statutory ground for each (§ 102 anticipation or § 103 obviousness)
- Real-party-in-interest disclosures naming every party with a stake in the outcome
- Proposed claim construction for any disputed terms
- Supporting prior art, properly authenticated as patents or printed publications
- An expert declaration addressing the technical merits, including motivation to combine (a credible reason a skilled engineer would have combined two references) and a reasonable expectation of success for obviousness theories
- USPTO filing fees per the current fee schedule, which is updated periodically; confirm current amounts at uspto.gov before filing
The Patent Owner’s Preliminary Response
After the petition is filed, the patent owner has three months to file a preliminary response. The goal at this stage is to persuade the PTAB not to institute. The patent owner may also submit supporting testimonial evidence, including expert declarations, with the preliminary response.
A well-supported preliminary response can sometimes prevent institutions and shift the leverage in any parallel district court case. It does not end the underlying dispute, since infringement claims usually continue in court, but it may remove the validity attack and change the negotiating posture.
Read More: Can a lawyer help defend against allegations of patent infringement in court?
Institution Decision Through Final Written Decision
The PTAB applies a “reasonable likelihood” standard at institution: the petitioner must show a reasonable likelihood of prevailing on at least one of the challenged claims. Following SAS Institute v. Iancu, if the PTAB institutes review, it must reach a final written decision on every challenged claim.
The Federal Circuit has since held that this same rule extends to every ground of unpatentability raised in the petition, not just every claim: in AC Technologies S.A. v. Amazon.com, Inc., 912 F.3d 1358 (Fed. Cir. 2019), the court held that once the Board institutes review, it must address all grounds raised by the petitioner, and that the Board “would have violated the statutory scheme” had it not done so. This is binding Federal Circuit precedent, not merely a USPTO policy choice. The Board also retains discretion to deny institution of the entire petition.
Trial Schedule and Appeal Rights
Once instituted, the trial is generally required to reach a final written decision within 12 months. The Board may extend that deadline in limited circumstances under statute or Board authorization, including joinder, consolidation, remand, or other statutory exceptions. The final written decision is appealable to the Federal Circuit. Institution decisions are generally insulated from appellate review under Cuozzo Speed Technologies v. Lee and Thryv, Inc. v. Click-To-Call Technologies, LP, subject to limited exceptions recognized in later case law (for example, constitutional questions or arguments that the PTAB acted outside its statutory authority).
Coordination With Parallel District Court Litigation
Most IPR petitioners are also defendants in a federal infringement case, so PTAB and court proceedings must be managed together. Three issues drive that coordination.
Stays of the Underlying Lawsuit
District courts have discretion to stay an infringement case once an IPR is filed or instituted. Stays are not automatic. Judges weigh how far the case has progressed, whether a stay would prejudice the patent owner, and whether the IPR would simplify the issues. A well-timed petition combined with a strong stay motion can be a meaningful tool for an accused infringer, although outcomes vary by court and case posture.
Claim Construction Alignment
The PTAB applies the Phillips standard (the same construction approach federal courts use, asking what a person of ordinary skill in the art would understand a claim term to mean in the context of the patent and its prosecution history). This replaced the broader “broadest reasonable interpretation” rule on November 13, 2018. Inconsistent positions across forums can draw scrutiny, and the Board must consider any prior district court or ITC construction placed in the record. For background on how courts handle these disputes, see our note on the Markman hearing.
Estoppel Timing
Section 315(e) estoppel attaches after the final written decision, not at the institution. Once that decision issues, the petitioner, real parties in interest, and privies cannot raise in the USPTO, district court, or ITC any prior-art-based invalidity ground they raised or “reasonably could have raised” at the PTAB. The scope of “reasonably could have raised” has been heavily litigated and applied inconsistently across district courts, so estoppel risk should be evaluated case by case.
Institution Strategy Factors
Petitioners are usually defendants under real-time pressure, and the institution stage has become dramatically more selective since early 2025. Overall institution rates fell to roughly 50% in USPTO fiscal year 2025 – a five-year low – with several individual months in 2025 seeing institution rates as low as 20–27%. Three factors tend to drive whether a petition gets through.
Prior Art Quality and Petition Structure
A thorough prior art search comes before drafting. Because estoppel may eventually bar what was raised or reasonably could have been raised, leaving strong art on the table can mean losing it in court, too. The PTAB will not rehabilitate a petition that buries its best argument, so highest-confidence anticipation and obviousness theories should come first, with redundant or weak grounds pruned.
Discretionary Denial Considerations
The Board has long had discretion to deny institution even when a petition meets the reasonable-likelihood threshold. Common factors that weigh against institutions include the following:
- Fintiv factors: When parallel ITC or district-court litigation is pending, the Board weighs whether duplicating that work serves the system. Fintiv has been cited as the single largest driver of discretionary denials in recent years – 58% of all discretionary denials issued during the USPTO’s 2025 “Interim Era” review of PTAB workload management cited Fintiv.
- Prior validity findings: Patents that have already survived earlier challenges in court, the ITC, or another PTAB proceeding are subject to stronger denial arguments.
- Real-party-in-interest issues: Failure to identify every party with a stake in the proceeding can defeat institution at the threshold.
- General Plastic factors: Multiple petitions against the same patent draw heightened scrutiny, and the PTAB regularly denies follow-on petitions that appear to be a second bite at the apple.
- Settled expectations: Since mid-2025, the Director has recognized a separate – and increasingly significant – discretionary denial factor based on the patent owner’s “settled expectations” in the patent, distinct from Fintiv. This factor weighed in favor of denial in roughly 60% of the denials issued during the same 2025 review period, and the PTAB has pointed to the patent having been in force for about six years or more as a relevant reference point. Petitioners should not assume that filing within the § 315(b) one-year window is sufficient; waiting too long after a patent issues, independent of any infringement suit, can itself support denial.
A Sotera stipulation (a commitment by the petitioner not to pursue the same invalidity grounds in parallel district-court litigation) may reduce the risk of a Fintiv denial in some cases. Filing early, before parallel litigation advances too far, also helps.
Recent Developments (Subject to Change)
USPTO post-grant policy has changed substantially and repeatedly since early 2025, and petitioners and patent owners should treat the discretionary-denial framework as unsettled rather than confirm current USPTO procedures and any pending guidance with official sources before relying on a specific approach. Key developments to date:
(1) a March 2025 memorandum temporarily split discretionary-denial briefing from merits briefing, with a separate Director-level threshold review of discretionary issues;
(2) an October 2025 memorandum eliminated that split, consolidating all institution decisions – discretionary and merits – into a single decision made by the Director in consultation with three PTAB judges, with most decisions issued as brief summary notices containing no reasoning;
and (3) the Director has designated several decisions from this period as precedential or informative, including ones recognizing “settled expectations” as an independent denial factor. Institution rates have fallen sharply as a result. Anyone evaluating whether to file should confirm the current state of this framework directly with USPTO guidance or counsel rather than relying on any static summary, including this one.
Joinder, Serial Petitions, and Director Review
Three procedural levers shape modern petitioner strategy:
- Joinder under § 315(c): A petitioner can ask to join an existing IPR brought by another party against the same patent. Joinder can sometimes function as a workaround for the one-year bar, but the joining petitioner generally takes the case as it stands, and the Board has denied joinder – even where the one-year bar would otherwise be avoided – where it found the request was not in the interests of justice, such as serial “me-too” filings or attempts to revive a time-barred petition after the IPR sought to be joined had settled or terminated .
- Serial petitions: As noted above, multiple petitions against the same patent are subject to General Plastic scrutiny.
- Director Review: Since 2021, parties can request that the USPTO Director review PTAB decisions, including institution rulings. As of October 2025, the Director now makes the initial institution decision directly (in consultation with three PTAB judges) in most cases, rather than reviewing a panel decision after the fact – making Director-level involvement the rule for institution generally, not just a post-decision review mechanism.
Defending a Patent in IPR
Patent owners run two distinct campaigns. The first focuses on stopping the proceedings before the institution. The second focuses on winning at trial without losing the patent or surrendering key claim scope.
Pushing Back at the Preliminary Response Stage
The preliminary response is the patent owner’s earliest opportunity to end the case. Common lines of attack include:
- Procedural defects: Untimely filing under the one-year bar, defective real-party-in-interest disclosure, or improper grounds outside §§ 102 and 103.
- Evidentiary defects: Prior art that is not properly authenticated as a printed publication, expert declarations lacking technical foundation, or missing motivation-to-combine analysis.
- Substantive weakness: Failure to meet the “reasonable likelihood” threshold on any challenged claim.
- Discretionary denial arguments: Parallel litigation advanced enough to make the IPR redundant, or other Fintiv-related considerations, as well as settled-expectations arguments based on how long the patent has been in force.
A focused response with one or two well-supported arguments often works better than a scattershot attack on everything.
Read More: How to Respond to a Patent Infringement Lawsuit
Trial Strategy and Claim Amendments
After the institution, the calendar speeds up. Patent owner response briefs, expert declarations, depositions, and the oral hearing all happen inside the 12-month window. Motions to amend claims have become more viable than in the PTAB’s early years, thanks to USPTO pilot programs and Federal Circuit guidance, though success remains challenging in practice.
Patent owners should also build the record with appeal in mind. Even when the patent owner expects to prevail at the Board, preserving a clean record for the Federal Circuit can affect outcomes on appeal.
Settlement and Termination Under § 317
Many IPRs settle before the final written decision. Under 35 U.S.C. § 317, parties can file a joint motion to terminate, and the PTAB generally grants it before a final written decision is issued, although the Board retains authority to proceed to a decision if termination would not serve the public interest. Settlement agreements must be filed with the PTAB, but parties can request that the agreement be treated as business confidential information and kept separate from the public file. Settlement before final written decision can also affect estoppel, since estoppel under § 315(e) generally requires a final written decision to attach.
Strategic Considerations Before You File or Respond
The biggest decisions in any IPR are made before the petition is filed. Estoppel, cost, and the dynamics of parallel litigation all turn on choices that may be hard to undo later.
Estoppel and What You Give Up by Filing
For a defendant in patent litigation, filing an IPR means surrendering a slate of district court invalidity options in exchange for one expedited PTAB shot. The practical consequence is that non-prior-art defenses (such as § 112 challenges, inequitable conduct, or inventorship disputes) become the only validity theories left in court once estoppel attaches.
A thorough pre-filing analysis weighs the strength of the prior art against the value of the defenses that would be preserved, the realistic odds of institution under current discretionary practice, and the timing of any parallel infringement case. Given how much institution odds have shifted since early 2025, that analysis should rely on current institution-rate data rather than historical averages. Filing without that analysis can leave a defendant with weaker tools in court than the defenses they started with.
Cost and Settlement Leverage
IPRs are often less expensive than full district-court invalidity litigation, though complex IPRs can still cost several hundred thousand dollars or more. Limited discovery, no jury, and a fixed schedule tend to keep budgets more predictable than open-ended federal litigation.
Institution often changes the negotiating dynamic. Many cases resolve through licensing, dismissal, or a global deal once the PTAB signals that one or more claims are vulnerable. Some disputes intensify after institution, particularly when the patent owner has strong commercial reasons to defend the patent through to a final decision.
Read More: The Role of an Intellectual Property Attorney in Patent Litigation
Frequently Asked Questions About Inter Partes Review
How long does an IPR take?
Most IPRs run roughly 18 months from petition filing to final written decision. The PTAB generally issues its institution decision within six months, and the trial is statutorily required to conclude within 12 months of institution, subject to limited extensions.
How much does an IPR cost?
Total fees vary widely by case complexity. USPTO filing fees alone run several thousand dollars per petition under the current fee schedule, and full counsel-led IPR proceedings often range into the mid-six figures or higher. Complex cases involving multiple petitions or technically dense art can be more expensive.
Can you appeal an IPR decision?
Final written decisions are appealable to the U.S. Court of Appeals for the Federal Circuit. Institution decisions are generally not appealable, subject to narrow exceptions recognized in later case law.
Can patent claims be amended during an IPR?
The patent owner can file a motion to amend claims after institution. Under USPTO pilot programs and recent guidance, amendments are more viable than they were in the early years, though they remain difficult in practice.
Does filing an IPR stay in parallel litigation?
Not automatically. District courts have discretion to grant a stay based on the stage of the case, prejudice to the patent owner, and whether the IPR would simplify the issues.
How Heimlich Law PC Helps With Patent Strategy and PTAB Decisions
An IPR petition or a recently served petition raises strategic questions long before the trial phase begins. Services include reviewing the strength of asserted claims, advising on whether to file or respond, conducting prior art analysis, and coordinating with patent litigation counsel where contested PTAB trial work is needed.
Heimlich Law PC is a boutique intellectual property firm in San Jose, California, serving solo inventors, startups, and small businesses across Silicon Valley and beyond. Alan Heimlich is a Registered Professional Engineer admitted to practice before the USPTO, with over 20 years of experience in IP law and lead counsel patent litigation in Federal court. The firm has also represented patent applicants in ex parte appeals to the Patent Trial and Appeal Board, which is a separate track from the inter partes proceedings described in this article.
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