New Process Fermentation Co. v. Maus was a United States Supreme Court case that dealt with the issue of patent infringement. The plaintiff, New Process Fermentation Co., had obtained a patent for a process of manufacturing alcohol from grain. The defendant, Maus, was accused of infringing on the patent by using the same process. The Supreme Court held that Maus had indeed infringed on the patent. The Court found that the patent was valid and that Maus had used the same process as described in the patent. The Court also held that Maus had not acted in good faith and had willfully infringed on the patent. The Court's decision was significant because it established that patent infringement could be found even if the accused party had not acted in bad faith. This decision has been cited in numerous subsequent cases and has been used to establish the principle that patent infringement can be found even if the accused party had not acted in bad faith.

In New Process Fermentation Co. v. Maus, the Supreme Court was asked to decide whether a patentee of an invention could recover damages from another party who had infringed upon their patent rights without any proof that they had suffered actual financial losses as a result of the infringement. The majority opinion held that such damages were not available under existing law and so the plaintiff's claim failed. However, in his dissenting opinion Justice Field argued that it would be unjust for someone to benefit financially from infringing on another person’s intellectual property rights without having to pay any compensation or penalty for doing so. He further argued that allowing this kind of behavior would encourage others to engage in similar activities with impunity and thus undermine public respect for patents and other forms of intellectual property protection more generally. As such, he concluded that there should be some form of remedy available even if no direct financial loss can be proven by the injured party