Our Patent Case Summaries provide a weekly summary of the precedential patent-related opinions issued by the Court of Appeals for the Federal Circuit and the opinions designated precedential or informative by the Patent Trial and Appeal Board.
Ironburg Inventions Ltd. v. Valve Corp.
No. 2024-2088 (Fed. Cir. (W.D. Wash.) June 18, 2026). Opinion by Hughes, joined by Chen. Concurring opinion by Stark.
Ironburg sued Valve for infringement of a patent directed to a video game controller. Before trial, Valve filed a first IPR petition challenging the patent claims followed by a second IPR petition focused on a newly discovered prior-art reference.
After the Patent Trial and Appeal Board issued a final written decision in the first IPR, Ironburg moved to terminate the second IPR based on estoppel under 35 U.S.C. § 315(e)(1). The Board granted the motion, finding that Ironburg had proven that “a skilled searcher conducting a diligent search reasonably could have been expected to discover” the new reference at issue in the second IPR.
A third party also filed an IPR challenging Ironburg’s patent claims, raising two new grounds that relied on different references than those cited in Valve’s petitions. Valve then amended its invalidity contentions in the district court litigation to assert the two grounds raised in the third party’s IPR. In response, Ironburg moved for IPR estoppel of the two grounds. The district court granted the motion, finding that a skilled searcher reasonably could have been expected to find the references.
After an initial appeal and remand, Ironburg renewed its motion for IPR estoppel and submitted additional evidence, including search results from a search company Ironburg retained to locate the references. Valve opposed the renewed motion, relying on evidence of its own search efforts undertaken before filing the first IPR petition.
The district court again granted Ironburg’s motion for IPR estoppel, finding that two of the references would have appeared in the results of Valve’s own searches, one reference was cited on the face of Ironburg’s patent, and the fourth reference was discoverable without “extraordinary measures” or “scorched earth” tactics.
Valve appealed, raising two main arguments: first, that the district court misapplied the “skilled searcher” standard with respect to Valve’s own search results, and second, that Ironburg’s search results were irrelevant because they were tainted by hindsight bias. The Federal Circuit agreed and thus reversed and remanded.
With respect to Valve’s own search results, the Federal Circuit noted that the classification searches performed by Valve’s search company returned thousands of references and that Ironburg provided no additional evidence demonstrating how Valve’s classification-based searches could have been narrowed through manual review. The court explained that it “do[es] not hold that manual review of search results will in all instances be necessary to establish discovery.” Instead, the court held “only that something more is required for estoppel when a classification search alone returns an unreviewable number of search results—a demand not met here.”
Turning to Ironburg’s evidence of its own search results, the Federal Circuit agreed with Valve that the evidence was irrelevant to the skilled searcher inquiry as tainted by hindsight bias. The court ruled that, “as a whole, the [Ironburg search] evidence fails to establish the discoverability of [the prior art] to a skilled searcher at the time of Valve’s IPR petition because it is tainted by hindsight.”
In a concurring opinion, Judge Stark acknowledged the lack of guidance on application of the skilled searcher standard. He noted that the court’s opinion “does not, of course, fill in all the details of IPR estoppel” but does “make several important contributions,” and he wrote separately to highlight them.
Judge Stark explained that, in his view, “a patentee relying on the skilled searcher test to estop a challenger, pursuant to § 315(e)(2), from pressing a particular ground of invalidity in district court, must prove at least the following: (i) the prior art reference(s) at issue were findable by a skilled searcher conducting a diligent search and (ii) the skilled searcher also reasonably would have been expected to discover, based on the reference(s) found, the invalidity ground the challenger seeks to assert in court.” Judge Stark noted that the court’s opinion centers on the first step of this analysis, as Valve did not separately challenge the second step. As to the first step, Judge Stark explained that the court’s opinion “holds that, in at least some circumstances, ‘something more’ than proving the mere accessibility of a prior art reference is required in order to establish a skilled searcher performing a diligent search would have found the reference.”
Tesla, Inc. v. Bulletproof Property Management, LLC
Nos. IPR2026-00204, -00205, -00219, -00222, -00227, -00228, -00229 (PTAB June 15, 2026) (designated informative on June 15, 2026). Decision by Squires.
Bulletproof filed a request for discretionary denial of institution of multiple IPR petitions filed by Tesla. The USPTO Director denied the request for several reasons.
To begin, the Director considered a co-pending district court litigation between the parties, but found that the absence of a scheduled trial date and Tesla’s “broad stipulation” on not pursuing certain invalidity grounds in the litigation “reduces the concern of inconsistent outcomes or significant duplication of efforts.” Next, the Director ruled that although one of the references relied on in the petition was previously considered by the Office, Tesla “demonstrate[d] that the Office erred in a manner material to the patentability of the claims.” The Director also determined that Bulletproof “had not developed strong settled expectations that favor discretionary denial.”
The Director ruled that “based on these arguments and evidence alone, discretionary denial is not appropriate.”
But the Director also determined that Tesla provided other arguments and evidence “further demonstrating that the Petitions should be considered on the merits,” citing the Office’s March 11, 2026 Memorandum titled Additional Discretionary Institution Considerations – U.S. Manufacturing and Small Business Use of AIA Proceedings. Tesla provided “evidence of its manufacturing activities in the United States, including that it manufactures the accused products in America.” Although Bulletproof alleged that the products “comprise 30% to 40% of components sourced in foreign countries,” it did not provide supporting evidence. The Director concluded that Tesla’s evidence of U.S. manufacturing “is more persuasive and further demonstrates that discretionary denial in these proceedings is not appropriate.”