The United States Constitution states, in Article III, Section 3: “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 Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted.”
Why? The Constitution doesn’t provide specific definitions of any other crimes; such matters were left up to the ordinary legislative process. Why did the Founding Fathers feel they had to include a definition of treason? And why did they make it so narrow? And why did they require two witnesses “to the same overt Act”? As I remember, that evidentiary requirement saved Aaron Burr from being convicted of treason for his plot to separate the Western states from the Union.
My guess would be, that in Britain the charge of “treason,” and the established procedure for declaring a person “attainted” or outlawed by vote of Parliament with no trial, both had historically been used as a weapon by whoever held power at the moment, to put down enemies and rivals; and the Framers wanted to make sure that kind of thing wouldn’t happen in the United States. But I have no cite for that. I don’t remember any discussion of this issue in The Federalist Papers, but, like most Americans who have any familiarity with that book, I didn’t read the whole thing, just the assigned sections.
Look at China or Cuba today. Do almost anything the government doesn’t like and you can be accused of treason, undermining the security of the state, etc.
Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort.
A new definition of treason was required because the existing definition in English law, as set out in the Statute of Treasons of 1352, defined high treason as actions which were done against the King. Although the English courts had often tried to define the term ‘the King’ as elastically as possible, it was recognised that there wasn’t a specific offence of treason against the state or the country. The phrases ‘levying War’, ‘adhering to their Enemies’ and ‘giving them Aid and Comfort’ were deliberate echoes of the wording of the 1352 Statute. In effect, all that this sentence was saying was ‘for “the King” read “the United States”’.
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.
This was just reiterating existing English law, specifically the Trials for Treason Act of 1696. The rule was actually an older one, although its exact significance had been the subject of some controversy, most famously during the attempted impeachment of the Earl of Strafford in 1641.
The Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted.
All this does is to prevent Congress passing laws which would disinherit the heirs of someone convicted of treason. In theory under English law, the property of anyone convicted of treason was confiscated to the Crown, but even in Britain it had long been recognised that this could be considered too draconian; it was just that the English practice had always been that this should be decided on a case-by-case basis, with the government usually (but not always) agreeing to return all or most of the property to the heirs.
There was more involved, however, than a simple desire to substitute nation for king. The English Tudor and Stuart dynasties had stretched the definition of treason to include almost any sort of resistance against the Crown–by deed or by word–as “constructive treason”. The framers sought to freeze in place the earlier, more restrictive definition of treason by writing it into the Constitution.
That was also a concern. However, a separate Constitutional provision outlaws “bills of attainder” for any crime, not just treason.
"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.’’ 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.
“Thus, the Framers adopted two of the three formulations and the phraseology of the English Statute of Treason enacted in 1350, but they conspicuously omitted the phrase defining as treason the ‘‘compass[ing] or imagin[ing] the death of our lord the King,’’ under which most of the English law of ‘‘constructive treason’’ had been developed. Beyond limiting the power of Congress to define treason, the clause also prescribes limitations upon Congress’ ability to make proof of the offense easy to establish and its ability to define punishment.”
Not that the notion of constructive treason had ever depended solely on the section about compassing the death of the King, with the English courts having found that phrases such as ‘levying war’ etc. could be almost as elastic. It was therefore always possible that the American courts could have developed their own form of constructive treason, although, of course, by going to the opposite extreme and interpreting this clause as narrowly as possible, they have never done so.