"Carbice Corp. v. American Patents Development Corp.", clarified that requiring patent licensees to buy other products as a condition of a patent license ("product tying") was misuse. American Patents Development Corp. held a patent for a dry ice transport enclosure. It required its customers only use their enclosure to transport dry ice from their exclusive distributor. The Supreme Court held that using patents to control an enclosure purchaser's other product purchases was patent misuse. (In a separate case a few months later, the Supreme Court held that Carbice's patent was invalid.)