A federal criminal law makes it a crime for any citizen of the United States not specifically authorized by the President to negotiate with a foreign government for the purpose of influencing the foreign government in relation to a dispute with the United States. The strongest constitutional ground for the validity of this law is that
under several of its enumerated powers, Congress may legislate to preserve the monopoly of the national government over the conduct of United States foreign affairs.  the President's inherent power to negotiate for the United States with foreign countries authorizes the President, even in the absence of statutory authorization, to punish citizens who engage in such negotiations without permission.  the law deals with foreign relations and therefore is not governed by the First Amendment. federal criminal laws dealing with international affairs need not be as specific as those dealing with domestic affairs.