By Joshua R. Rich —

Under President Trump, the U.S. Patent and Trademark Office has sought to encourage the issuance of more patents and limit the ability to challenge them in post-grant proceedings; since John Squires was sworn in as Director, that process has accelerated tremendously. On October 16, 2025, the Office issued proposed rules limiting the circumstances under which inter partes review can be instituted and conditioning institution upon a waiver of any other prior art challenge. There is no doubt that the proposed rules would limit the frequency and availability of IPR to challenge the validity of patents. But there is a real question whether the proposed rules are legal.

Importantly, notice of proposed rulemaking was not identified as the beginning of notice-and-comment rulemaking (and all of the administrative requirements that such a process would entail). Rather, the notice indicates that “[t]he changes proposed by this rulemaking involve rules of agency practice and procedure, and/or interpretive rules, and do not require notice-and-comment rulemaking.” It is questionable whether that assertion is correct, as the proposed rules would have a significant impact on accused infringers’ (and other patent challengers’) substantive rights, but the USPTO is seeking to push the rules through quickly by allowing only thirty days for the submission of any comments. As a result, the rules may be in place sooner, but there is a very real threat that their enforcement will be blocked if the rulemaking process is challenged under the Administrative Procedure Act.

There are four basic proposed changes in the IPR rules:

• Unless every petitioner submits a stipulation to the USPTO and “any other tribunal where it is litigating or later litigates regarding the challenged patent” indicating that it (and any privy or real party in interest) will forego any anticipation or obviousness argument in any other proceeding, inter partes review cannot be instituted or maintained.

• Inter partes review cannot be instituted or maintained if a challenged claim or an independent claim from which the claim depends has been found not anticipated or obvious in a district court (either upon trial or by summary judgment), the U.S. International Trade Commission (in either an initial or final determination), the Board itself (in an inter partes review or post-grant review), in ex parte reexamination, or in the Federal Circuit, even in proceedings not involving the petitioner.

• Inter partes review cannot be instituted or maintained if there is a parallel proceeding in a district court, the ITC, or another Board proceeding where it is more likely than not that a decision will be reached before the final written decision in the inter partes review, even in proceedings not involving the petitioner.

• If the Board finds there are extraordinary circumstances that would justify an exception to the rules above, they can refer a petition to the Director to decide whether to institute. But extraordinary circumstances are limited: they include a bad faith action to prevent review or a substantial change in the statute or Supreme Court precedent that renders the prior challenge irrelevant, but do not include new prior art or argument, Federal Circuit precedent, or a prior challenger’s failure to appeal. And sanctions can be imposed if a petition claiming extraordinary circumstances is found to be frivolous or abusive.

The first of these provisions appears to be the most legally suspect. The America Invents Act that created inter partes review identified circumstances under which such an inter partes review could prevent anticipation or obviousness challenges in other proceedings. Under 35 U.S.C. § 315(e)(1):

The petitioner in an inter partes review of a claim in a patent under this chapter that results in a final written decision under section 318(a), or the real party in interest or privy of the petitioner, may not request or maintain a proceeding before the Office with respect to that claim on any ground that the petitioner raised or reasonably could have raised during that inter partes review.

That estoppel is narrower than the proposed rule in several ways. Most importantly, it limits estoppel to any ground that the petitioner raised or reasonably could have raised in the inter partes review, not all anticipation and obviousness arguments. But it also only takes effect if a final written decision results from a proceeding; the proposed stipulation is required for institution. So there is a gap between the two forms of estoppel for review that settles before a final written opinion.

Given the carefully crafted scope of statutory estoppel, an administrative stipulation provision that would have the effect of creating a broader estoppel is likely to be held to exceed the USPTO’s discretion in implementing the statute. Under the statutory construction maxim “expressio unius est exclusion alterius,” Congress’s decision to provided only limited estoppel suggests it did not intend to bar all anticipation and obviousness challenges (and not in all instituted reviews). Any regulations on the same topic – like the stipulation requirement – of different scope would therefore likely be unlawful for the agency to implement.

But the regulations that would bar inter partes review based on another party’s challenge are legally suspect as well. To be clear, these regulations would not prevent inter partes review of just the same arguments or art, or arguments by the same party. They would prevent any inter partes review if a prior challenger failed in its challenge as well, even if also based on unrelated art. Effectively, this would give some level of offensive res judicata effect to a patent owner’s win against a prior art challenge. That is not the law. To the contrary, res judicata in patent cases is not mutual: patent challengers are not barred by another challenger’s failure, but a single finding of invalidity prevents assertion of invalidated claims against another accused infringer. That question was squarely considered and determined by the Supreme Court in Blonder Tongue v. Univ. of Ill. Found., 402 U.S. 313 (1971). While the decision did not involve whether administrative proceedings could have different rules (especially administrative proceedings that did not exist until decades later), it is hard to believe that courts would view contrary regulations to be appropriate.

While there appear to be substantial potential problems with the proposed rules, they may serve several beneficial purposes nonetheless. First, just as the bipartisan Patent Eligibility Restoration Act introduced by Senators Tillis and Coons has, they can provide a framework for discussion of potential changes to the Patent Act.  Second, they reinforce the seriousness that the USPTO has shown in trying to strengthen patent eligibility. Further, they may discourage (or sensitize courts) to some of the abusive use of inter partes review. And there is always the possibility that courts will not invalidate the proposed rules, if adopted. But most likely, they are most useful as pushing Congress into action to restore patent protections that have been narrowed over the years.