Walker Process Counterclaim

Refers to a type of U.S. antitrust counterclaim based on §2 of the Sherman Act for wrongful efforts to enforce a patent obtained by fraud on the patent office or inequitable conduct. The term is derived from a seminal U.S. Supreme court case Walker Process Equipment, Inc. v. Food Machinery & Chemical Corp., 382 U.S. 172 (1965). Although common and effective in the 1970s and 1980s, more recent court decisions have severely limited the effectiveness of Walker Process counterclaims.