Mr. Justice HOLMES delivered the opinion of the Court.
This is a bill in equity brought by the State of Missouri to prevent a game warden of the United States from attempting to enforce the Migratory Bird Treaty Act of July 3, 1918, c. 128, 40 Stat. 755, and the regulations made by the Secretary of Agriculture in pursuance of the same. The ground of the bill is that the statute is an unconstitutional interference with the rights reserved to the States by the Tenth Amendment, and that the acts of the defendant done and threatened under that authority invade the sovereign right of the State and contravene its will manifested in statutes. The State also alleges a pecuniary interest, as owner of the wild birds within its borders and otherwise, admitted by the Government to be sufficient, but it is enough that the bill is a reasonable and proper means to assert the alleged quasi sovereign rights of a State. A motion to dismiss was sustained by the District Court on the ground that the Act of Congress is constitutional. The State appeals.
On December 8, 1916, a treaty between the United States and Great Britain was proclaimed by the President. It recited that many species of birds in their annual migrations traversed many parts of the United States and of Canada, that they were of great value as a source of food and in destroying insects injurious to vegetation, but were in danger of extermination through lack of adequate protection. It therefore provided for specified closed seasons and protection in other forms, and agreed that the two powers would take or propose to their lawmaking bodies the necessary measures for carrying the treaty out. 39 Stat. 1702. The above mentioned act of July 3, 1918, entitled an act to give effect to the convention, prohibited the killing, capturing or selling any of the migratory birds included in the terms of the treaty except as permitted by regulations compatible with those terms, to be made by the Secretary of Agriculture. Regulations were proclaimed on July 31, and October 25, 1918. 40 Stat. 1812, 1863. It is unnecessary to go into any details, because, as we have said, the question raised is the general one whether the treaty and statute are void as an interference with the rights reserved to the States.
To answer this question it is not enough to refer to the Tenth Amendment, reserving the powers not delegated to the United States, because by Article 2, Section 2, the power to make treaties is delegated expressly, and by Article 6 treaties made under the authority of the United States, along with the Constitution and laws of the United States made in pursuance thereof, are declared the supreme law of the land. If the treaty is valid there can be no dispute about the validity of the statute under Article 1, Section 8, as a necessary and proper means to execute the powers of the Government. The language of the Constitution as to the supremacy of treaties being general, the question before us is narrowed to an inquiry into the ground upon which the present supposed exception is placed.
It is said that a treaty cannot be valid if it infringes the Constitution, that there are limits, therefore, to the treaty-making power, and that one such limit is that what an act of Congress could not do unaided, in derogation of the powers reserved to the States, a treaty cannot do. An earlier act of Congress that attempted by itself and not in pursuance of a treaty to regulate the killing of migratory birds within the States had been held bad in the District Court. United States v. Shauver, 214 Fed. 154. United States v. McCullagh, 221 Fed. 288. Those decisions were supported by arguments that migratory birds were owned by the States in their sovereign capacity for the benefit of their people, and that under cases like Geer v. Connecticut, 161 U.S. 519, 16 Sup. Ct. 600, this control was one that Congress had no power to displace. The same argument is supposed to apply now with equal force. Whether the two cases cited were decided rightly or not they cannot be accepted as a test of the treaty power. Acts of Congress are the supreme law of the land only when made in pursuance of the Constitution, while treaties are declared to be so when made under the authority of the United States. It is open to question whether the authority of the United States means more than the formal acts prescribed to make the convention. We do not mean to imply that there are no qualifications to the treaty- making power; but they must be ascertained in a different way. It is obvious that there may be matters of the sharpest exigency for the national well being that an act of Congress could not deal with but that a treaty followed by such an act could, and it is not lightly to be assumed that, in matters requiring national action, 'a power which must belong to and somewhere reside in every civilized government' is not to be found. What was said in that case with regard to the powers of the States applies with equal force to the powers of the nation in cases where the States individually are incompetent to act. We are not yet discussing the particular case before us but only are considering the validity of the test proposed. 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. It was enough for them to realize or to hope that they had created an organism; it has taken a century and has cost their successors much sweat and blood to prove that they created a nation. The case before us must be considered in the light of out whole experience and not merely in that of what was said a hundred years ago. The treaty in question does not contravene any prohibitory words to be found in the Constitution. The only question is whether it is forbidden by some invisible radiation from the general terms of the Tenth Amendment. We must consider what this country has become in deciding what that amendment has reserved.
The State as we have intimated founds its claim of exclusive authority upon an assertion of title to migratory birds, an assertion that is embodied in statute. No doubt it is true that as between a State and its inhabitants the State may regulate the killing and sale of such birds, but it does not follow that its authority is exclusive of paramount powers. To put the claim of the State upon title is to lean upon a slender reed. Wild birds are not in the possession of anyone; and possession is the beginning of ownership. The whole foundation of the State's rights is the presence within their jurisdiction of birds that yesterday had not arrived, tomorrow may be in another State and in a week a thousand miles away. If we are to be accurate we cannot put the case of the State upon higher ground than that the treaty deals with creatures that for the moment are within the state borders, that it must be carried out by officers of the United States within the same territory, and that but for the treaty the State would be free to regulate this subject itself.
As most of the laws of the United States are carried out within the States and as many of them deal with matters which in the silence of such laws the State might regulate, such general grounds are not enough to support Missouri's claim. Valid treaties of course 'are as binding within the territorial limits of the States as they are elsewhere throughout the dominion of the United States.' No doubt the great body of private relations usually fall within the control of the State, but a treaty may override its power....
Here a national interest of very nearly the first magnitude is involved. It can be protected only by national action in concert with that of another power. The subject matter is only transitorily within the State and has no permanent habitat therein. But for the treaty and the statute there soon might be no birds for any powers to deal with. We see nothing in the Constitution that compels the Government to sit by while a food supply is cut off and the protectors of our forests and our crops are destroyed. It is not sufficient to rely upon the States. The reliance is vain, and were it otherwise, the question is whether the United States is forbidden to act. We are of opinion that the treaty and statute must be upheld.
Mr. Justice VAN DEVANTER and Mr. Justice PITNEY dissent.