Dreyfus v. Searle was a United States Supreme Court case that addressed the issue of patent infringement. The case involved a dispute between two companies, Dreyfus and Searle, over a patent for a machine used to make paper bags. Dreyfus had obtained a patent for the machine in 1876, and Searle had subsequently obtained a patent for a similar machine in 1878. The Supreme Court held that Searle had infringed upon Dreyfus' patent, as the two machines were substantially similar. The Court noted that the two machines were not identical, but that the differences between them were minor and did not affect the overall function of the machines. The Court also noted that Searle had been aware of Dreyfus' patent when they obtained their own patent, and that Searle had not made any effort to distinguish their machine from Dreyfus'. The Court's decision in Dreyfus v. Searle established that patent infringement can occur even when the infringing device is not identical to the patented device. The Court's decision also established that patent infringement can occur when the infringing device is substantially similar to the patented device, and when the infringer was aware of the patent when they obtained their own patent.

Justice Field delivered the dissenting opinion in Dreyfus v. Searle, arguing that the majority's decision was incorrect and should be reversed. He argued that a patentee does not have an exclusive right to use his invention unless he has complied with all of the requirements of obtaining a valid patent as set forth by Congress. In this case, Justice Field believed that Dreyfus had failed to meet these requirements because he did not provide sufficient evidence showing how his invention worked or what it could do for consumers. Furthermore, Justice Field noted that even if Dreyfus had met all of the statutory requirements for obtaining a valid patent, there were still other issues at play which would prevent him from having an exclusive right to use his invention; namely, prior art and public policy considerations such as whether or not granting patents on certain inventions is beneficial to society overall. Ultimately, Justice Field concluded that since Dreyfus had failed to comply with all of the necessary statutory requirements for obtaining a valid patent and since there were other important factors at play which weighed against granting him an exclusive right over his invention anyway - regardless of any potential validity - then Searle should prevail in this case and retain its own rights over its own version of similar technology without interference from Dreyfus' claims.