[4] Disgruntled with these rulings, Congress then empowered the State Department to negotiate with the United Kingdom—which at the time still largely handled the foreign relations of Canada—a treaty pertaining to this issue.

In an opinion authored by Justice Holmes, the Supreme Court dismissed Missouri's demand for an injunction against the federal government, holding that protection of a state's quasi-sovereign right to regulate game is insufficient jurisdictional basis to enjoin enforcement of the laws at issue.

In the course of his judgment, Justice Holmes remarked on the nature of the Constitution as an "organism" that must be interpreted in contemporaneous terms: With regard to that we may add that when we are dealing with words that also are a constituent act, like the Constitution of the United States, we must realize that they have called into life a being the development of which could not have been foreseen completely by the most gifted of its begetters.

Many legal analysts have argued that the decision implies that Congress and the President can essentially amend the Constitution by means of treaties with other countries.

Legal scholar Judith Resnik contests the implication that Missouri allows for treaties to expand the federal government's power, arguing that in the decades since the decision, courts have ruled that the Commerce Clause of the U.S. Constitution provides Congress with broader regulatory power without the need for a treaty.