here's an excerpt from hostage's post that's worth repeating:
Treason is the higher crime of the group and is the only one that carries the highest penalty of death. But death is not mandatory, as the penalty can be imprisonment and fine. The amount of imprisonment and fine is unlimited. For example, John Brennan, if convicted of treason, can be imprisoned for life and ruined financially. If a member of government is found to have leaked to the Chicoms the identities of US agents in China that resulted in their deaths, then it's likely the death penalty will follow to the leaker.
Article 3 Sec. 3 Defines treason.
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.
Penalty also codified.
Penalty: U.S. Code Title 18: Death, or not less than 5 years’ imprisonment and not more than life imprisonment without the possibility of parole (minimum fine of $10,000, if not sentenced to death). Any person convicted of treason against the United States will permanently lose the right to ever hold or run for public office anywhere in any capacity within the United States.[