In the 1937 case Leitch Manufacturing Co. v. Barber Company, the U.S. Supreme Court ruled in favor of Leitch Manufacturing Co., stating that a patent cannot be used to extend monopoly power beyond its statutory limit by tying it with an unpatented product or process. The Barber Company held patents for both a method and apparatus for producing concrete blocks but sold machines only on condition that buyers would use them exclusively with their patented method, which involved using certain materials also supplied by them at higher prices than market rates. This was deemed as an unlawful extension of patent rights into areas not covered by the patent itself (the doctrine of "misuse"). The court stated that while a patentee may control use of his invention, he cannot give it "commercial value" derived solely from statutory right to exclude others from making, using or selling it and then insist upon payment for such added value through royalties tied to purchase or use of another article.

In the dissenting opinion for Leitch Manufacturing Co. v. Barber Company, it was argued that the patent in question should not have been invalidated because it represented a new and useful process, even if its individual components were already known. The dissent contended that just because each step of a process is old or well-known does not mean their combination cannot be novel and therefore patentable. It was further asserted that this ruling could discourage innovation by denying protection to inventors who create new processes from existing elements, which is often how technological progress occurs.