United States v. Masonite Corp.  United States v. Masonite Corp., 316 U.S. 265 (1942), is a United States Supreme Court decision that limited the scope of the 1926 Supreme Court decision in the "General Electric" case that had exempted patent licensing agreements from antitrust law's prohibition of price fixing. The Court did so by applying the doctrine of the Court's recent "Interstate Circuit" hub-and-spoke conspiracy decision. Masonite Corporation, the principal defendant in this case, and defendants Celotex Corporation, Certain-Teed Products Corporation, Johns-Manville Sales Corporation, Insulite Company, Flintkote Company, National Gypsum Company, Wood Conversion Company, Armstrong Cork Company, and Dant & Russell, Inc. were all competitors engaged in manufacturing and selling building materials, including hardboard. Hardboard is a strong, hard, dense, grainless, synthetic board made from heat and pressure treated wood chips, and is claimed in a Masonite patent. Masonite sued Celotex for patent infringement and prevailed. The parties settled the dispute with a 1933 "agency" agreement. Then Masonite sent and proposed the same agreement to others of the defendants, and each executed the agreement between 1933 and 1934. As each agreement was made, Masonite informed the signatory of the existence and terms of each of the agreements that Masonite had previously made with the other companies, and sent copies of the new agreement to those companies that had previously executed similar contracts. Masonite sent the agency agreement to Insulite, but that company refused to sign; Masonite then sued a dealer who handled Insulite's hardboard, charging infringement of one of Masonite's patents, and Insulite undertook the defense. But Insulite then signed the same agency agreement in 1935. The agency agreements were modified in 1936 and an agreement relating to them was signed by each defendant, so that each party knew at that time that Masonite proposed to make substantially identical agreements with the others. The agreement provided that it should become effective only when all the parties had agreed to it. The contracts between Masonite and the other defendants each designated the other defendant as an "agent" and appointed it as a "del credere factor" to sell Masonite's hardboard products. The contracts also provided that Masonite would fix uniform prices for itself and the others on hardboard they manufactured and sold:  Masonite agreed to designate from time to time the minimum selling price and the maximum terms and conditions of sale at which the "agent" might sell Masonite's products.