In Tool Company v. Norris, the Supreme Court of the United States was asked to determine whether a patentee has exclusive rights in an invention even if it is not novel or useful. The plaintiff, Tool Company, held a patent for an improved method of making nails and sought damages from defendant Norris for infringement on their patent. The court ruled that although the invention may not be novel or useful, as long as it is new and non-obvious then the inventor can still have exclusive rights over it under US Patent Law. This ruling established that inventors are entitled to protection regardless of novelty or usefulness when they make improvements upon existing inventions which are deemed new and non-obvious by courts.

In Tool Company v. Norris, the Supreme Court was asked to decide whether a patentee of an invention could bring suit against another for infringement after the expiration of his patent term. The majority opinion held that such suits were not allowed under existing law and thus dismissed the case. In dissent, Justice Field argued that Congress had intended to allow post-expiration suits when it passed legislation granting patents in 1836 and again in 1861. He noted that this interpretation would be consistent with other laws allowing similar actions by copyright holders after their copyrights expired as well as with general principles of equity which should apply equally to all inventors regardless of when their patents expire or are infringed upon. Furthermore, he argued that denying post-expiration suits would create a perverse incentive for potential infringers who might wait until just before a patent's expiration date before infringing on it knowing they could escape liability if caught afterwards due to lack of legal recourse available to the inventor at that point.