This crime, established by Article III, Section 3 of the Constitution, is the only one specifically created by the document. The crime occurs when one “levies war” against the United States or gives “aid and comfort” to its enemies.

A person can be convicted of treason only if he or she confesses, or if there are two witnesses to the act of treason. Treason is also a ground for impeachment of the President or other federal officials. – The United States Constitution, What It Says, What It Means, A Hip Pocket Guide