United States v. United States Gypsum Co.

A group of gypsum wallboard manufacturers (defendants), including United States Gypsum Co., routinely called each other to confirm prices charged to specific customers. The United States (plaintiff) charged the manufacturers with criminally violating the Sherman Act by colluding to restrain price competition. The district court instructed the jury that it could presume the manufacturers intended to fix prices if it found the price-verification calls actually affected prices. The jury convicted, but the court of appeals reversed based on that instruction, and the government appealed.