Migratory Bird Treaty of 1918

The Migratory Bird Treaty of 1918 between the United States and Great Britain prohibited the killing of many species of birds that traversed certain parts of the United States and Canada. Such species were of great value both as a source of food and because they destroyed insects injurious to vegetation, but they were in danger of extermination through lack of protection.

The state of Missouri sought to have the treaty declared an unconstitutional interference with the rights that are reserved to the states by the Tenth Amendment to the Constitution. In Missouri v. Holland, 252 U.S. 416, 40 S.Ct. 382, 64 L.Ed. 641 (1920), the Supreme Court held that a valid treaty must prevail over state law, even if a federal statute on the subject would be unconstitutional. Acts of Congress are the supreme law of the land only when made pursuant to the Constitution, and treaties are accorded the same status when made under the authority of the United States.