In the case of De La Vergne Refrigerating Machine Company v. Featherstone (1892), the U.S Supreme Court was tasked with determining whether a patent infringement had occurred. The De La Vergne Refrigerating Machine Company claimed that Featherstone, who manufactured and sold refrigeration machines, infringed upon their patented design for an ammonia condenser used in refrigeration systems. However, after examining both designs closely, the court concluded that there were significant differences between them which made it clear that they were not identical nor equivalent to each other in function or operation. Therefore, no infringement had taken place as alleged by De La Vergne Refrigerating Machine Company against Featherstone's machine design and production activities.

In the dissenting opinion for De La Vergne Refrigerating Machine Company v. Featherstone, Justice Brewer argued that the patent in question was not a new invention but rather an improvement of existing technology. He believed that while improvements can be patented, they should not extend to cover the original device or process being improved upon. In this case, he felt that De La Vergne's patent on an improved refrigeration machine did not give them exclusive rights over all ammonia-based refrigeration machines as it was merely an enhancement of pre-existing methods and devices using ammonia for cooling purposes. Therefore, Featherstone’s use of similar technology did not infringe on De La Vergne's patent rights according to Justice Brewer's interpretation.