This is a list of cases reported in volume 252 of United States Reports, decided by the Supreme Court of the United States in 1920. Justices of the Supreme Court at the time of volume 252 U.S. The Supreme Court is established by Article III, Section 1 of the Constitution of the United States, which says: "The judicial Power of the United States, shall be vested in one supreme Court . . .". The size of the Court is not specified; the Constitution leaves it to Congress to set the number of justices. Under the Judiciary Act of 1789 Congress originally fixed the number of justices at six (one chief justice and five associate justices). Since 1789 Congress has varied the size of the Court from six to seven, nine, ten, and back to nine justices (always including one chief justice). When the cases in volume 252 were decided the Court comprised the following nine members: Notable Case in 252 U.S. Missouri v. Holland In Missouri v. Holland, 252 U.S. 416 (1920), the Supreme Court considered the extent to which international legal obligations are incorporated into federal law. The case centered on the constitutionality of the Migratory Bird Treaty Act of 1918, which prohibited the killing, capturing, and selling of certain migratory birds pursuant to an earlier treaty between the U.S. and the United Kingdom. The state of Missouri challenged enforcement of the Act within its jurisdiction, arguing that the regulation of game was not expressly delegated by the U.S. Constitution to the federal government, and was therefore reserved for the states under the Tenth Amendment. The Court upheld the Act as a valid exercise of the federal government's treaty power, with the supremacy clause of the Constitution elevating treaties above state law. Citation style Under the Judiciary Act of 1789 the federal court structure at the time comprised District Courts, which had general trial jurisdiction; Circuit Courts, which had mixed trial and appellate (from the US District Courts) jurisdiction; and the United States Supreme Court, which had appellate jurisdiction over the federal District and Circuit courts—and for certain issues over state courts. The Supreme Court also had limited original jurisdiction (i.e., in which cases could be filed directly with the Supreme Court without first having been heard by a lower federal or state court). There were one or more federal District Courts and/or Circuit Courts in each state, territory,