The Federal Circuit Court of Appeals’ recent decision in Focus Products Group International, LLC v. Kartri Sales Co., Inc., No. 2023-1446 (Fed. Cir. Sept. 30, 2025) reversed summary judgment of infringement on two patents and vacated on a third. The Court held the district court erred in both claim construction and application of its infringement analysis by failing to properly find the patent file history disavowed subject matter relied upon to find infringement. The disavowal was critical because the claim language broadly covered the product’s configuration found to be infringing by the district court.
A patent’s claim scope can be narrowed only if the file history contains a “clean and unmistakable” disavowal that overcomes the heavy presumption that claim terms carry their full and ordinary meaning. In practice, that standard has been difficult to meet even when applicant’s arguments overcame prior art and examiner rejections. The accused device in Focus Products was a shower curtain ring with a flat upper edge (shown here). The Federal Circuit relied on several statements by the examiner that the application’s claims covered different species—one for a ring with projections and another for a ring with a “flat upper edge.” The patentee elected to withdraw claims covering a ring with a flat upper edge without objecting to the examiner’s definition. And in the Notice of Allowance, the examiner again stated that a “flat upper edge” fell outside the scope of the applicant’s election and invited the applicant to challenge that designation.
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