Commentary by Jon Roland
It is a fundamental principle of law that an agent cannot acquire additional powers from his principal by entering into an agreement with the agent of another principal. He may make agreements, if he has the authority to make any agreements at all, only to exercise powers already delegated to him. Officials of the U.S. government are agents of the people under the terms of the Constitution, which defines and limits the powers that they may exercise, and those limits apply not only within the territorial boundaries of the United States, but everywhere and over all persons, regardless of whether they are citizens or not.
The correct opinion in this case is that of Black. The concurring opinions of Frankfurter and Harlan are erroneous in that they base their position on the offense being capital. Clark, in dissent, is correct in saying the capital nature of the charge is irrelevant, but incorrect in saying that treaties may extend U.S. criminal jurisdiction in the way he suggests, to other than U.S. military personnel, on territory that is not embassy territory but merely foreign territory under temporary U.S. control under the terms of a status of forces agreement. He would, however, have been correct if the territory had been that of a U.S. embassy or equivalent diplomatic facility, and the offense had been prosecuted under civilian criminal statutes authorized by the "laws of nations" clause.
The logic is very clear. Congress may acquire more power only by amendment of the Constitution, and treaties are not among the alternatives in Art. V for such amendment. However, this is in conflict with Missouri v. Holland, 252 U.S. 416 (1920), and in dictum this decision did not reject the error made in that case:
There is nothing in Missouri v. Holland, 252 U.S. 416 , which is contrary to the position taken here. There the Court carefully noted that the treaty involved was not inconsistent with any specific provision of the Constitution. The Court was concerned with the Tenth Amendment which reserves to the States or the people all power not delegated to the National Government. To the extent that the United States can validly make treaties, the people and the States have delegated their power to the National Government and the Tenth Amendment is no barrier.
The people and the states delegated no such power, and no evidence was offered that they did. We can be sure that if they thought the Treaty Clause were to be interpreted to evade the limitations of powers in the Constitution, they would never have ratified the Constitution.
This brings up the subject of the Logic of Judges.
For more on this see also