A Sotera stipulation is a voluntary promise a patent challenger files with the Patent Trial and Appeal Board, agreeing not to raise in a parallel district court case any invalidity ground it raised or reasonably could have raised in its Inter Partes Review petition. Challengers file it to reduce the overlap between the two proceedings and improve their odds of getting the IPR instituted. After USPTO guidance issued in March 2025, the stipulation is still influential, but it no longer functions as a near-automatic ticket past discretionary denial.
What the Stipulation Commits You To
The name comes from Sotera Wireless, Inc. v. Masimo Corp., IPR2020-01019, which the Board designated as precedential on December 1, 2020. The relevant part is Section II.A, which addressed how a petitioner’s broad stipulation should weigh in the Board’s discretionary denial analysis.
A broad Sotera stipulation contains two promises. First, the petitioner will not raise in district court the specific invalidity grounds asserted in the IPR petition. Second, and this is the part that gives the stipulation its force, the petitioner will not raise any grounds that could have been reasonably raised in the petition. That second promise sweeps in prior art patents and printed publications the challenger knew about, should have found through reasonable searching, or chose to leave out. In effect, the challenger gives up any patent-or-publication invalidity argument in court, not just the ones it actually filed.
A narrower alternative exists, sometimes called a Sand Revolution stipulation after Sand Revolution II, LLC v. Continental Intermodal Group–Trucking LLC (IPR2019-01393). Under that version, the petitioner drops only the exact grounds asserted in the petition and keeps everything else available for court. The Board has consistently found this narrower commitment less persuasive because it does little to eliminate parallel litigation of similar theories on different prior art. When the Board has evaluated narrow stipulations, it found the overlap factor weighed only “somewhat against denial.” Petitioners who want the Board to take the stipulation seriously almost always file the broad version.
The Fintiv Problem It Solves
The stipulation exists as a response to the framework in Apple Inc. v. Fintiv, Inc., IPR2020-00019. Under Fintiv, the Board decides whether to decline to hear a case in light of a parallel court proceeding by weighing several factors, including the timing of the district court trial relative to the Board’s final decision deadline, how much the court has already invested in the case, and how much the invalidity issues overlap between the two forums.
Overlap is where the stipulation does its work. By promising not to litigate the same or reasonably-related invalidity theories in court, the challenger addresses the Board’s concern about duplicative proceedings head-on. The Sotera decision itself said a broad stipulation weighs strongly in favor of the Board moving forward. Combined with a strong showing on the merits, a broad stipulation has been enough to overcome an otherwise unfavorable Fintiv calculation, even where a court trial is coming up relatively soon. It’s not absolute. If trial is imminent and the district court has already put significant work into claim construction and discovery, the Board may still deny institution.
What the March 2025 Guidance Changed
For years after Sotera, filing a broad stipulation came close to guaranteeing institution. In March 2025 the USPTO rescinded its earlier interim procedure and restored a more holistic Fintiv analysis. Under the current framework, a timely-filed Sotera stipulation is “highly relevant, but will not be dispositive by itself.” The Director asks whether the stipulation “materially reduces overlap between the proceedings.” When the challenger relies on related prior art across multiple proceedings, or keeps several different invalidity theories alive in court, the stipulation may not count for much because the real-world efficiency gain is small.
The guidance also separated the discretionary-denial arguments into their own briefing, rather than folding them into the petition or the patent owner’s preliminary response. The bottom line for a challenger: a Sotera stipulation is still critical, but it no longer clears the discretionary denial hurdle by itself. The Board looks harder at whether the specific stipulation actually eliminates meaningful duplication in the specific case.
When to File
The stipulation has to be on the record before the Board decides whether to institute. USPTO guidance instructs petitioners to file “as soon as practicable” so the patent owner has a fair chance to address it in the discretionary denial briefing. Most petitioners include the stipulation language in the petition itself or file it as a short standalone document soon after.
Waiting is dangerous. If the patent owner files its discretionary denial brief before the stipulation appears, the petitioner has left the overlap concern unaddressed at exactly the moment it matters most. Once the Board issues its institution decision under 35 U.S.C. § 314(a), that decision is final and not appealable, and the window closes for good.
How It Differs From Statutory Estoppel
A Sotera stipulation is often confused with the statutory estoppel that federal patent law imposes after an IPR ends. They work differently and, after a recent Federal Circuit decision, cover different ground.
Statutory estoppel under 35 U.S.C. § 315(e)(2) bars a petitioner from asserting in a civil action that a claim is invalid on any ground it “raised or reasonably could have raised” during the review. But estoppel only kicks in after the Board issues a final written decision. If the review is instituted and then settles or terminates early, statutory estoppel does not attach. A Sotera stipulation binds the petitioner the moment the Board accepts it and institutes.
The Federal Circuit’s May 2025 decision in Ingenico Inc. v. IOENGINE, LLC read statutory estoppel narrowly. The court held that estoppel only bars the petitioner from arguing invalidity in district court under Sections 102 or 103 based on patents or printed publications. It does not prevent the petitioner from using those same patents and publications as evidence supporting invalidity theories that could not have been raised in the IPR at all, such as arguments that the invention was already known, on sale, or in public use.
That matters because a broad Sotera stipulation may reach further than what estoppel would eventually require. A challenger who stipulates away every ground that “could have been reasonably raised” in the IPR is giving up arguments that Ingenico would otherwise let it keep. The stipulation needed to get through the Fintiv gate may cost more in district court than the estoppel statute would have imposed on its own.
What Defenses Survive in District Court
Once the Board accepts the stipulation and institutes review, the petitioner is bound in the parallel court case. The patent owner can enforce it by asking the district court to exclude any invalidity defense within the stipulation’s scope. In practice, the challenger loses the ability to put its patent-and-publication invalidity theories in front of a jury.
What survives are defenses that could never have been brought in an IPR in the first place. Federal law limits IPR to invalidity challenges based on prior art patents or printed publications. Arguments outside that category remain available in court: that the patented invention was on sale before the filing date, that it was in public use, or that it was known or used by others. These defenses turn on physical evidence and witness testimony rather than published documents.
The trade-off is real. A challenger whose strongest evidence is a collection of prior art publications may find its best arguments locked up at the Board. If the Board upholds the patent, there is no second chance to put that evidence to a jury. The petitioner buys a faster expert evaluation of its best prior art in exchange for flexibility in court.
Parallel ITC Investigations
The March 2025 guidance confirmed the Board applies Fintiv when a parallel International Trade Commission investigation is pending. A Sotera stipulation can help in that setting, but only if the stipulation’s language explicitly covers the ITC proceeding. In Arashi Vision Inc. v. GoPro, Inc. (IPR2025-00017), the Board declined to credit a Sotera stipulation because it addressed only district court litigation and said nothing about the ITC investigation.
Petitioners with parallel proceedings in both a district court and the ITC need to draft accordingly. A stipulation limited to one forum leaves the overlap concern unresolved in the other. The Board has signaled it is more inclined to deny institution when an ITC investigation is on track to finish before the Board’s final written decision deadline, and a stipulation alone will not necessarily overcome an ITC case nearing its final determination.