Graver Tank & Manufacturing Co. v. Linde Air Products Co. is a landmark U.S. Supreme Court case that established the doctrine of equivalents in patent law, allowing a court to hold a party liable for patent infringement even if the infringing product or process does not fall within the literal scope of the patent claims. This decision underscores the importance of protecting the essence of an invention, rather than just its literal expression, to prevent unscrupulous parties from circumventing patent rights through insubstantial changes.