The Key City is a United States Supreme Court case that was decided in 1872. The case involved a dispute between the City of Key West and the United States government over the ownership of a submerged tract of land in the harbor of Key West. The City of Key West claimed that it had acquired title to the submerged land by virtue of its ownership of the adjacent upland property. The United States government argued that the submerged land was part of the public domain and that the City of Key West had no right to it. The Supreme Court held that the City of Key West had acquired title to the submerged land by virtue of its ownership of the adjacent upland property. The Court reasoned that the City of Key West had acquired title to the submerged land by virtue of its ownership of the adjacent upland property, and that the United States government had no right to the submerged land. The Court further held that the City of Key West had the right to use the submerged land for any purpose it deemed necessary, including the construction of docks and wharves. In conclusion, the Supreme Court held that the City of Key West had acquired title to the submerged land by virtue of its ownership of the adjacent upland property, and that the United States government had no right to the submerged land. The Court further held that the City of Key West had the right to use the submerged land for any purpose it deemed necessary.

In The Key City, the Supreme Court was asked to decide whether a contract between two parties that had been partially performed could be enforced. Justice Field wrote the dissenting opinion in which he argued that contracts should not be enforced if they are contrary to public policy or morals. He reasoned that it is up to courts of equity and law to determine what constitutes an illegal contract, and therefore any such agreement should not be enforceable. Furthermore, he noted that even when a contract does not violate public policy or morality, there may still exist circumstances under which its enforcement would lead to injustice; thus it is necessary for courts of equity and law have discretion in deciding whether or not such agreements can be enforced. In conclusion, Justice Field argued against enforcing contracts whose terms are deemed immoral by society at large as well as those where enforcement would result in inequity despite their legality.