Article III, Section 3, Clause 1:
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 Treason Clause is a product of the awareness of the Framers of the
numerous and dangerous excrescences which had disfigured the English law of treason and was therefore intended to put it beyond the power of Congress to
extend the crime and punishment of treason.1 The debate in the Convention, remarks in the ratifying conventions, and contemporaneous public comment make clear that a restrictive concept of the crime was imposed and that ordinary partisan divisions within political society were not to be escalated by the stronger into capital charges of treason, as so often had happened in England.2
Thus, the Framers adopted two of the three formulations and the phraseology of the English Statute of Treason enacted in 1350,3 but they conspicuously omitted the phrase defining as treason the
compass[ing] or imagin[ing] the death of our lord the King,4 under which most of the English law of
constructive treason had been developed.5 Beyond limiting the power of Congress to define treason,6 the clause also prescribes limitations upon Congress’s ability to make proof of the offense easy to establish7 and its ability to define punishment.8