IRONBURG INVENTIONS LTD. v. VALVE CORPORATION

IRONBURG INVENTIONS LTD. v. VALVE CORPORATION The Federal Circuit held that the district court lacked sufficient evidence to estop Valve from asserting the Kotkin ground because a classification search returning an unreviewably large number of references did not establish reasonable discoverability. It also held that the Cardinal IP searches used to support estoppel of the Willner-Koji-Raymond ground were tainted by hindsight and therefore not probative. The decision makes clear that § 315(e)(2) estoppel requires concrete, time-appropriate proof of what a diligent skilled searcher reasonably would have found, not broad search hits or hindsight-reconstructed searches. Reversed and remanded for the district court to consider invalidity of the '525 patent in light of the Kotkin and Willner-Koji-Raymond grounds. The asserted patent covers a game controller with back controls; after an earlier IPR and trial, the dispute on remand centered on whether Valve was estopped from asserting two later-identified obviousness grounds. For Kotkin, the district court relied on evidence that Valve's search vendor used classifications that would have included the reference, but the relevant search returned more than 26,000 references and was not meaningfully narrowed. The Federal Circuit held that, at least where a classification search returns an unreviewable volume of results, 'something more' is required to show the reference was reasonably discoverable for § 315(e)(2) estoppel. For the Willner-Koji-Raymond ground, the court found Ironburg's Cardinal IP evidence infected by hindsight because citation searches captured later-arising references and later search steps were shaped by those results. The court did not resolve whether the skilled-searcher inquiry is legal or factual, or the full scope of what it means to 'discover' an invalidity ground, but reaffirmed that estoppel is assessed as of the time of the IPR petition. § 103 remand precedential § 103 remand precedential § 103 remand