The Mabey and Cooper case was a landmark decision by the United States Supreme Court in 1871. The case involved a dispute between two companies, Mabey and Cooper, over the ownership of a patent for a new type of steam engine. Mabey had obtained a patent for the engine, but Cooper had independently developed a similar engine and was attempting to obtain a patent for it. The Supreme Court ruled in favor of Mabey, finding that Cooper had infringed upon Mabey's patent. The Court held that a patent is a property right, and that the patentee has the exclusive right to make, use, and sell the invention. The Court also held that the patentee has the right to prevent others from making, using, or selling the invention without the patentee's permission. The decision established the principle that patent rights are exclusive and that patent infringement is a violation of the patentee's rights. The decision also established the principle that a patentee can recover damages for patent infringement. The Mabey and Cooper case is an important precedent in patent law and has been cited in numerous subsequent cases.

In the case of Mabey and Cooper, the Supreme Court was tasked with determining whether a contract between two parties could be enforced when one party had been misled by false statements made by the other. The majority opinion held that such contracts were not enforceable because they lacked mutual assent due to one party's reliance on false information. However, in his dissenting opinion Justice Field argued that if both parties entered into an agreement without fraud or coercion then it should be upheld regardless of any misrepresentations made prior to its formation. He further noted that allowing such contracts would encourage honesty and good faith among contracting parties as each would have an incentive to provide accurate information about their respective positions before entering into agreements. Ultimately, he concluded that upholding these types of contracts was necessary for maintaining public confidence in contractual obligations and protecting individuals from being taken advantage of through fraudulent means.