A person commits the crime of treason if he levies war against his state or country or sides to its enemies, giving them aid and comfort. Treason is a crime under federal and some state laws. Treason is made a high crime, punishable by death, under federal law by Article III, section 3 of the U.S. Constitution: "Treason against the United States shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort."
Under this article of the Constitution, 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. Treason requires overt acts such as giving sensitive government security secrets to other countries, even if such countries are not enemies. Treason can include spying on behalf of a foreign power or divulging military secrets.
The majority of states outlaw treason in their constitutions or statutes similar to those in the U.S. Constitution. There have been only two successful prosecutions for treason on the state level, that of Thomas Dorr in Rhode Island and that of John Brown in Virginia.