... The forefathers also had suffered from disloyalty. Success of the Revolution had been threatened by the adherence of a considerable part of the population to the King. The Continental Congress adopted a resolution after a report by its 'Committee on Spies' which in effect declared that all persons residing within any colony owed allegiance to it, and that if any such persons adhered to the King of Great Britain, giving him aid and comfort, they were guilty of treason, and which urged the colonies to pass laws for punishment of such offenders 'as shall be provably attainted of open deed.' Many of the colonies complied, and a variety of laws, mostly modeled on English law, resulted. Some of the legislation in later years became so broad and loose as to make treason of mere utterance of opinion ...
... The idea that loyalty will ultimately be given to a government only so long as it deserves loyalty and that opposition to its abuses is not treason has made our government tolerant of opposition based on differences of opinion that in some parts of the world would have kept the hangman busy. But the basic law of treason in this country was framed by men who, as we have seen, were taught by experience and by history to fear abuse of the treason charge almost as much as they feared treason itself. The interplay in the Convention of their two fears accounts for the problem which faces us today ...
... The concern uppermost in the framers' minds, that mere mental attitudes or expressions should not be treason, influenced both definition of the crime and procedure for its trial ...
... Treason of adherence to an enemy was old in the law. It consisted of breaking allegiance to one's own King by forming an attachment to his enemy. Its scope was comprehensive, its requirements indeterminate. It might be predicated on intellecutal or emotional sympathy with the for, or merely lack of zeal in the cause of one's own country. That was not the kind of disloyalty the framers thought should constitute treason. They promptly accepted the proposal to restrict it to cases where also there was conduct which was 'giving them aid and comfort.'
'Aid and comfort' was defined by Lord Reading in the Casement trial comprehensively, as it should be, and yet probably with as much precision as the nature of the matter will permit: '... an act which strengthens or tends to strengthen the enemies of the King in the conduct of a war against the King, that is in law the giving of aid and comfort' and 'an act which weakens or tends to weaken the power of the King and of the country to resist or to attack the enemies of the King and the country ... is ... giving of aid and comfort.' Lord Reading explained it, as we think one must, in terms of an 'act.' It is not easy, if indeed possible, to think of a way in which 'aid and comfort' and be 'given' to an enemy except by some kind of action. Its very nature partakes of a deed or physical activity as opposed to a mental operation.
Thus the crime of treason consists of two elements: adherence to the enemy; and rendering him aid and comfort. A citizen intellectually or emotionally may favor the enemy and harbor sympathies or convictions disloyal to this country's policy or interest, but so long as he commits no act of aid and comfort to the enemy, there is no treason. 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.