In the United States v. Masonite Corporation et al., 1941, the Supreme Court ruled that a price-fixing scheme between manufacturers and distributors was in violation of antitrust laws. The case involved Masonite Corporation and several other companies who had entered into agreements to fix prices for hardboard, a type of building material. These agreements were made with both domestic and foreign distributors, effectively creating an international cartel which controlled the price of hardboard worldwide. The court held that these arrangements constituted illegal restraints on trade under Section 1 of the Sherman Act because they eliminated competition among distributors and allowed manufacturers to control retail prices.

In the dissenting opinion for UNITED STATES v. MASONITE CORPORATION et al., Justice Roberts disagreed with the majority's interpretation of patent law and its application to price-fixing agreements. He argued that a patent holder has exclusive rights over their invention, including setting prices for licensees who wish to use it. In his view, this right is not inherently anti-competitive or monopolistic as long as other competitors are free to invent and sell similar products without infringing on the original patent. Therefore, he believed that Masonite Corporation's pricing agreement with its licensees did not violate antitrust laws because it was within their rights as a patent holder. Furthermore, he criticized the majority for expanding antitrust laws beyond what Congress intended by applying them to lawful exercises of patents rights.