Breaking allegiance to the U.S. government, through acts of war against it or aiding its enemy.

Article III, section 3, of the Constitution limits treason to acts of war against the United States or giving aid and comfort to its enemies. The crime must be proved by the testimony of at least two witnesses to the same overt act or by the defendant’s confession in open court. Treason is the only federal crime for which both the substantive and evidential elements of culpability are spelled out in the Constitution. By defining the crime narrowly, the Framers sought to prevent the political abuse of treason law.

The Whiskey Rebellion and Fries Rebellion in the 1790’s resulted in three treason convictions in the federal circuit court for Pennsylvania, but presidential pardons for all the defendants forestalled appeals to the Supreme Court. The Court’s first ruling on the treason clause came in Ex parte Bollmann[case]Bollmann, Ex parte[Bollmann, Ex parte] (1807), one of the cases arising from Aaron BurrBurr, Aaron’s western conspiracy (Burr was charged with attempting to separate the western part of the country from the rest of the nation). Speaking for the Court, Chief Justice John Marshall held that war is an essential element of treason; absent armed hostilities, a conspiracy to make war does not qualify as treason. While later presiding at Burr’s trial in the federal circuit court for Virginia, Marshall instructed the jury that the Constitution requires overt acts of treason; mere plots to commit such acts are not sufficient. The instruction and Burr’s acquittal infuriated President Thomas Jefferson, who had pressed hard for a conviction.

No treason convictions were appealed to the Court before World War II, a conflict that raised several key issues. In Cramer v. United States[case]Cramer v. United States[Cramer v. United States] (1945), the first conviction reviewed, the Court ruled that acts not treasonous on their face may be rendered treasonous by the defendant’s treasonous intent. However, the conviction was nevertheless overturned on the grounds that the acts alleged were too ambiguous to justify an inference of treasonous intent from the surrounding circumstances. Two years later in a similar case, Haupt v. United States[case]Haupt v. United States[Haupt v. United States] (1947), the conviction was upheld on the grounds that the defendant’s acts, though also ambiguous, were of a nature to justify an inference of treasonous intent. Together, the cases hold that the inference must arise from the acts alleged as well as from the surrounding circumstances. The Court also settled the issue of whether treason can be committed beyond the territorial limits of the United States. In Kawakita v. United States[case]Kawakita v. United States[Kawakita v. United States] (1952), the Court held that U.S. citizens are liable for acts of treason committed anywhere in the world. Unlike most other crimes, treason has no geographical boundaries.

• Chapin, Bradley. The American Law of Treason: Revolutionary and Early National Origins. Seattle: University of Washington Press, 1964.
• Hurst, James Willard. The Law of Treason in the United States. Westport, Conn.: Greenwood Press, 1971.
• Kennedy, Roger G. Burr, Hamilton, and Jefferson: A Study in Character. New York: Oxford University Press, 2000.
• Lomask, Milton. Aaron Burr: The Conspiracy and the Years of Exile, 1805-1836. New York: Farrar, Straus, Giroux, 1982.

Burr, Aaron

Constitutional law

Jefferson, Thomas

Marshall, John

World War II