Graver Tank & Mfg. Co. v. Linde Air Products Co. 339 US 605 (1950) Summary sbonomo
This was a Supreme Court case dealing with an electric welding process. The court relied upon the doctrine of equivalents to expand a patent monopoly to cover processes involving non-alkaline earth metals, even though the claims of the patent specifically were limited to such metals. This case exemplifies the fine line that is drawn between preventing harm to the public as a result of granting patents for minute differences, and withholding knowledge from being used by the public that is not directly claimed in a patent.