The Wood-Paper Patent case was a dispute between two paper manufacturers, the Wood Paper Company and the American Paper Company. The Wood Paper Company had patented a process for making paper from wood pulp, and the American Paper Company was accused of infringing on the patent. The case was heard by the Supreme Court of the United States in 1873. The Supreme Court ruled in favor of the Wood Paper Company, finding that the American Paper Company had indeed infringed on the patent. The Court held that the patent was valid and that the American Paper Company had used the patented process without permission. The Court also held that the patent was not invalidated by the fact that the process had been used by others prior to the patent being granted. The Court's decision was significant in that it established the principle that a patent is valid even if the process or invention has been used by others prior to the patent being granted. This ruling has been cited in numerous subsequent cases and has become an important part of patent law.

In The Wood-Paper Patent, the Supreme Court was asked to decide whether a patent for an improved method of making paper from wood pulp should be granted. Justice Field delivered the dissenting opinion in which he argued that the invention did not meet all of the requirements necessary for a valid patent. He noted that while it may have been novel and useful, there was no evidence presented to show that it had any element of novelty or inventiveness beyond what already existed in prior art. Furthermore, he argued that since this process involved only mechanical steps and did not involve any new chemical processes or combinations, it could not be considered as being truly inventive. As such, Justice Field concluded that granting a patent would amount to unjustly extending monopoly rights over something which is essentially just an improvement on existing technology rather than something entirely new and innovative.