The Banks v. The Mayor was a case heard by the United States Supreme Court in 1868. The case involved a dispute between the City of New York and the Bank of the United States. The Bank of the United States had been chartered by Congress in 1816 and was the first national bank in the United States. The City of New York had passed a law in 1857 that imposed a tax on the Bank of the United States. The Bank of the United States argued that the tax was unconstitutional because it violated the Bank's right to be free from state taxation. The Supreme Court ruled in favor of the Bank of the United States, holding that the tax was unconstitutional. The Court reasoned that the Bank of the United States was a federal institution and was therefore immune from state taxation. The Court also held that the Bank of the United States was a necessary and proper instrumentality of the federal government and was therefore entitled to the same privileges and immunities as other federal institutions. The Banks v. The Mayor case was an important decision in the development of the doctrine of federal supremacy. The decision established that the federal government had the power to create and regulate national banks, and that state governments could not interfere with the operations of these banks. The decision also established that the federal government had the power to protect its own institutions from state taxation.

In The Banks v. The Mayor, the Supreme Court was asked to decide whether a municipal ordinance in Washington D.C., which prohibited African Americans from working as cab drivers and hackmen, violated the Thirteenth Amendment of the United States Constitution. In an 8-1 decision, with Justice Field dissenting, it was held that such ordinances were unconstitutional because they constituted involuntary servitude or slavery within the meaning of the Thirteenth Amendment. Justice Field argued that while he agreed with his colleagues on their interpretation of what constitutes involuntary servitude under this amendment, he believed that Congress had not intended for it to apply to local laws like this one since there is no language in either section 1 or 2 of the amendment specifically addressing state and municipal legislation prohibiting certain occupations by African Americans. He further argued that if Congress had wanted these types of laws to be covered by this amendment then they would have included specific language stating so when drafting it; thus leaving any decisions regarding such matters up to each individual state's legislature instead.