However, Congress has, at times, passed statutes creating related offenses that undermine the government or the national security, such as sedition in the 1798 Alien and Sedition Acts, or espionage and sedition in the 1917 Espionage Act, which do not require the testimony of two witnesses and have a much broader definition than Article Three treason. For example, some well-known spies have been convicted of espionage rather than treason.
The Constitution does not itself create the offense; it only restricts the definition (the first paragraph), permits Congress to create the offense, and restricts any punishment for treason to only the convicted (the second paragraph). The crime is prohibited by legislation passed by Congress. Therefore the United States Code at 18 U.S.C. § 2381 states "whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States." The requirement of testimony of two witnesses was inherited from the British Treason Act 1695 (Since 1945, however, this has been abolished in British law and treason cases are now subject to the same rules of evidence and procedure as a murder trial, but the US requirement still stands barring an amendment).