Besser Mfg. Co. v. United States, 343 U.S. 444 (1951), is a 1951 patent–antitrust decision of the United States Supreme Court in which the Court upheld a ruling that the dominant U.S. manufacturer of concrete block–making machines violated the antitrust laws when it acquired its two principal competitors (attaining a 65% market share), bought important patents, made bad–faith threats of patent infringement suits, and entered into patent licensing agreements in which the parties were given veto powers over any prospective additional licensees. The Supreme Court approved the district court's grant of compulsory, reasonable–royalty licensing of the patents and compulsory sales of patented machines, holding that such relief "is a well–recognized remedy where patent abuses are proved in antitru