Opinions — Tuesday, June 23, 2026

In Maxeon Solar Pte. Ltd. v. Hanwha Solutions Corp., the Federal Circuit dismissed the appeal and cross-appeal from a Patent Trial and Appeal Board decision in IPR2024-01203 under Federal Rule of Appellate Procedure 42(b) based on the parties' stipulation. The court ordered that each side shall bear its own costs and issued the order as mandate on June 23, 2026.

The Federal Circuit affirmed summary judgment of noninfringement in favor of Intel Corporation on two patents owned by PACT XPP Schweiz AG relating to computer processor architecture. For the '301 patent, which claimed processors "adapted for programmably processing sequences" of data, the district court found that the accused products processed only instruction sequences, not data sequences, and that PACT forfeited its capability-based infringement theory by raising it for the first time in a motion for reconsideration. For the '593 patent, which required a "physically dedicated connection" between cores and memory, the district court construed the term based on PACT's prosecution disclaimer to require end-to-end exclusivity, excluding shared pathways.

The court's analysis turned on two procedural and substantive constraints that proved fatal to PACT's case. On the '301 patent, the panel enforced the rule against raising new infringement theories post-summary judgment, rejecting PACT's attempt to pivot from arguing actual data processing to arguing mere capability of data processing—a distinct theory under Finjan and Intel Corp. v. ITC—only after an adverse ruling. On the '593 patent, the court applied prosecution history estoppel principles to bind PACT to its reexamination arguments distinguishing prior art, holding that PACT's statement that a dedicated connection must be "specifically devoted" and "not to other units" foreclosed a construction permitting partially shared pathways where only "at least one segment" was exclusive.

The Federal Circuit affirmed the District of Massachusetts's grant of summary judgment invalidating all claims of Enanta Pharmaceuticals' U.S. Patent No. 11,358,953 as anticipated by Pfizer's prior public disclosure of nirmatrelvir, the active ingredient in Paxlovid®. The central issue was whether Enanta's non-provisional application, which issued as the '953 patent and disclosed a substituent containing "—NHC(O)—C₁-C₁₂-alkyl" (one to twelve carbon atoms), could claim priority to an earlier provisional application that disclosed "—NHC(O)—C₂-C₁₂-alkyl" (two to twelve carbon atoms). Enanta argued the provisional contained an obvious typographical error that would have been apparent to a person of ordinary skill in the art, thus providing adequate written description support under 35 U.S.C. § 112 for the later-filed claims. The Federal Circuit held that the provisional application did not satisfy the written description requirement because it specifically disclosed only C₂-C₁₂ alkyl, not C₁ alkyl, and the disclosure of "2" cannot provide written description support for "1"—even if other portions of the provisional arguably contained inconsistencies. Because the '953 patent could not claim the provisional's July 2020 priority date, Pfizer's April 2021 disclosure of nirmatrelvir anticipated the claims.

The decision reinforces that written description support for priority purposes requires actual disclosure in the earlier application, not what might be inferred from purported errors elsewhere in the specification. The court distinguished this case from traditional genus-species written description disputes like Ariad and In re Ruschig, and from cases concerning judicial or PTO correction of errors in issued patents under Novo Industries and In re Oda, instead applying the straightforward requirement that each application in a priority chain must describe the claimed invention with sufficient detail to demonstrate possession. The court rejected expert testimony suggesting that a typographical error in a general definition of "alkyl" elsewhere in the provisional could establish written description support for a specific substituent, emphasizing that extrinsic evidence cannot vary plain patent language and that entitlement to a filing date extends only to what is actually disclosed. The analogy to ethanol versus methanol underscores the court's unwillingness to read disclosure of one specific chemical integer as inherently disclosing another, even structurally adjacent compounds, absent explicit textual support.