Chemcast Corp. v. Arco Industries Corp.
Court of Appeals for the Federal Circuit
913 F.2d 923 (1990)
Chemcast (plaintiff) sued Arco (defendant) for infringing its patent on a grommet used to seal openings in sheet-metal panels; Arco counterclaimed that the patent was invalid for failing to disclose the best mode under 35 U.S.C. § 112. The patent's claims described only broad physical-property ranges for the grommet material rather than naming the specific compound the inventor actually preferred and used, even though the manufacturer and formula number could have been disclosed despite the exact chemical formula being a third-party trade secret. The district court found the best mode was not disclosed and invalidated the patent; Chemcast appealed.
Whether the best-mode requirement is satisfied when an inventor broadly discloses preferred properties for a claim element without disclosing the specific preferred material by name.