Gillette v. Energizer, a claim to 3 blades covers 4 blades

Of Gillette v. Energizer, concerning U.S. Patent No. 6,212,777, contemplate arguments in the Insituform case, Insituform Technologies v. Cat Contracting, 58 USPQ2d 1392 (CAFC 2001) (unpublished) [and earlier decisions in the litigation], as discussed in “Insituform: Festo for the Festophile,” Intellectual Property Today, pp. 48-49 (May 2001)[available LEXIS]. Therein, an issue was whether a claim to ONE vacuum cup covered an accused embodiment with TWO vacuum cups, and the CAFC concluded because TWO vacuum cups imparted different properties, the claim to one vacuum cup did NOT cover two vacuum cups.

But a claim to three blades in a razor does cover four blades.