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).^[1] 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 306 were decided the Court comprised the following members (Justice Brandeis retired in the midst of the cases reported in volume 306):

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, or other geographical region.

The Judiciary Act of 1891 created the United States Courts of Appeals and reassigned the jurisdiction of most routine appeals from the district and circuit courts to these appellate courts. The Act created nine new courts that were originally known as the "United States Circuit Courts of Appeals." The new courts had jurisdiction over most appeals of lower court decisions. The Supreme Court could review either legal issues that a court of appeals certified or decisions of court of appeals by writ of certiorari. On January 1, 1912, the effective date of the Judicial Code of 1911, the old Circuit Courts were abolished, with their remaining trial court jurisdiction transferred to the U.S. District Courts.

[a] Frankfurter took no part in the case (he joined the Court on January 30, 1939, and so did not participate in cases argued before that date)

[b] Roberts took no part in the case

[c] Stone took no part in the case

[d] Hughes took no part in the case

• [1] Case reports in volume 306 from Library of Congress
• [2] Case reports in volume 306 from Court Listener
• [3] Case reports in volume 306 from the Caselaw Access Project of Harvard Law School
• [4] Case reports in volume 306 from Google Scholar
• [5] Case reports in volume 306 from Justia
• [6] Case reports in volume 306 from Open Jurist
• Website of the United States Supreme Court
• United States Courts website about the Supreme Court
• National Archives, Records of the Supreme Court of the United States
• American Bar Association, How Does the Supreme Court Work?
• The Supreme Court Historical Society