Treaty

An agreement or compact between nations; a formal written engagement or league between independent powers or tribes. By the general law of nations, a treaty is, in its nature, a contract, not a legislative act. It does not generally effect of itself the object to be accomplished, especially so far as its operation is infraterritorial; but waits to be carried into execution by the sovereign power of the respective parties to the instrument. In the United States, however, a different of the land; and it is, consequently, regarded in courts of justice as equivalent to an act of the legislature, whenever it is of a nature to operate of itself, without the aid of any legislative provision. But when the terms of the stipulation import a contract; when either of the parties engages to perform a particular act; the treaty addresses itself to the political, not the judicial, department, and the legislature must execute the contract before it can become a rule for the court.

Foster v. Neilson, 2 Pet. 232, 314.