Treason

Treason is a crime involving betrayal of a state, commonly by aiding its enemies or attempting to overthrow its government. Its legal definition and required proof vary by jurisdiction.

State: A political organization that exercises authority over a territory and its population. Treason is defined as betrayal of a political state.
Treason Clause: The United States Constitution's narrow definition of treason and rules for conviction. It limits treason to levying war against the United States or adhering to its enemies.
United States v. Burr: The 1807 treason trial of former U.S. vice president Aaron Burr, who was acquitted. The case tested whether an alleged conspiracy and its preparations amounted to levying war.
High treason: A grave offense against a sovereign or state, distinguished from lesser forms of treason in some legal systems. The distinction reflects how some systems classify betrayal of the state.
Attainder: A legal process that historically imposed punishment and forfeiture without an ordinary criminal trial. English treason law once used attainder to impose severe penalties on the condemned.
Allegiance: A bond of loyalty or obligation owed to a ruler, state, or institution. Many treason laws require a legally recognized duty of loyalty.
Two-witness rule: An evidentiary rule requiring two witnesses to the same overt act for a treason conviction in the United States. The Constitution makes this safeguard part of proving treason.
R v Casement: The 1916 British treason trial of Roger Casement, convicted for seeking German support for Irish independence. The prosecution treated wartime assistance to an enemy as treason.
Misprision of treason: The offense of knowing about treason and failing to disclose it to authorities, where recognized by law. It punishes concealment of treason rather than committing the betrayal itself.
Ex post facto law: A law that retroactively criminalizes conduct or increases punishment for it. Constitutional bans on such laws constrain how treason can be defined after events.

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