The Supreme Court, of the federal United States, decides Foster v. Neilson:

       A treaty is in the nature of a contract between two nations, not a legislative act.  It does not generally effect, of itself, the object to be accomplished, especially so far as its operation is infra-territorial, but is carried into execution by the sovereign power of the respective parties to the instrument.

       In the [u]nited States, a different principle is established.  Our Constitution declares a treaty to be the law of the land.  It is consequently to be regarded in courts of justice as equivalent to an act of the legislature whenever it operates of itself, without the aid of any legislative provision.  But when the terms of the stipulation import a contract, when either of the parties engage 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.

       [added 12/31/2021]