The United States inherited the English common law from the British Empire, and the Founding Fathers recognised the danger of what James Madison called "new-fangled and artificial treasons".
The words "giving them aid and comfort" were added by the Committee of Detail to further narrow the definition of treason.
The constitutional definition did not immediately deter prosecutors from attempting to prosecute for levying war people who had not directly done so.
In Ex parte Bollman (1807) the Supreme Court rejected arguments by prosecutors to the effect that enlisting an army of men against the United States could amount to levying war before they actually assembled.
"[8] In United States v. Burr the Court held that mere intent to commit treason was not sufficient either.
On the other hand, a citizen may take actions which do aid and comfort the enemy—making a speech critical of the government or opposing its measures, profiteering, striking in defense plants or essential work, and the hundred other things which impair our cohesion and diminish our strength—but if there is no adherence to the enemy in this, if there is no intent to betray, there is no treason.”[10]