ARTICLE III section 3

SECTION. 3.
 Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.


The Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted.

Treason is the only crime defined in the Constitution. In England, treason charges had been used to punish criticism of the government. To avoid such abuse, the framers of the Constitution established very specific elements of the crime that must be proved—and the standard of evidence for that proof. Furthermore, although an attainder of treason could deprive a traitor of his assets, Congress could not punish the heirs of a traitor by revoking their inheritance—a practice known as corruption of blood.



The definition of treason was tested early in the republic. President Thomas Jefferson sought to prosecute his former vice president and political adversary, Aaron Burr, for treason in 1807. Burr was tried in federal court at Richmond, Virginia, with Chief Justice John Marshall serving in his capacity as circuit court judge. In his rulings on the evidence, Marshall construed the definition of treason very narrowly, requiring that two witnesses must testify that Burr was actually involved in levying war, not just conspiracy. Based on Marshall’s rulings, the jury acquitted Burr of all charges.
Because of the high standard of proof for treason, convictions have been rare in U.S. history—and those who were convicted were frequently pardoned. Participants in the Whiskey Rebellion of 1794 were pardoned, as were southern combatants during the Civil War. It was not until 1947 that the Supreme Court acted to uphold a treason conviction.


But the U.S. government prosecuted disloyal citizens on other grounds—and with less proof than required for treason. In 1917, Congress passed the Espionage Act, making it illegal to convey unauthorized information on national defense. In 1951, Julius and Ethel Rosenberg—both devoted members of the American Communist Party—were convicted under the Espionage Act for conspiring to transmit atomic secrets to the Soviet Union. When the Supreme Court refused to hear their appeals, they were both executed on June 19, 1953. After the Cold War ended, evidence from U.S. and Soviet intelligence files implicated Julius as a spy, but it appears that Ethel was only tangentially involved.