Treason is the only crime defined in the U.S. Constitution. Specifically, the charge is adhering to or giving comfort to the enemies of the United States. It can be proven if the accused admits to it in open court or on the testimony of two eyewitnesses.
http://www.sfgate.com/crime/article/Few-ever-charged-or-convicted-of-treason-in-U-S-2843242.php
How many people have been executed for Treason against America?
Category:People executed for treason against the United States!
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Pages in category “People executed for treason against the United States”
The following 3 pages are in this category, out of 3 total. This list may not reflect recent changes (learn more).
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Moses Dunbar
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Thomas Hickey (soldier)
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William Bruce Mumford
List of people convicted of treason agains the United States-Wikipedia
Philip Vigol and John Mitchell, convicted of treason and sentenced to hanging; pardoned by George Washington; see Whiskey Rebellion.
John Fries, the leader of Fries’ Rebellion, convicted of treason in 1800 along with two accomplices, and pardoned that same year by John Adams.
Governor Thomas Dorr 1844, convicted of treason against the state of Rhode Island; see Dorr Rebellion; released in 1845; civil rights restored in 1851; verdict annulled in 1854.
John Brown, convicted of treason against the Commonwealth of Virginia in 1859 and executed for attempting to organize armed resistance to slavery.
Aaron Dwight Stevens, took part in John Brown’s raid and was executed in 1860 for treason against Virginia.
William Bruce Mumford, convicted of treason and hanged in 1862 for tearing down a United States flag during the American Civil War.
Walter Allen was convicted of treason on September 16, 1922 for taking part in the 1921 Miner’s March with the coal companies and the US Army on Blair Mountain, West Virginia. He was sentenced to 10 years and fined. During his appeal to the Supreme Court he disappeared while out on bail. United Mineworkers of America leader William Blizzard was acquitted of the charge of treason by the jury on May 25, 1922.[11]
Martin James Monti, United States Army Air Forces pilot, convicted of treason for defecting to the Waffen SS in 1944. He was paroled in 1960.
Robert Henry Best, convicted of treason on April 16, 1948 and served a life sentence.
Iva Toguri D’Aquino, who is frequently identified by the name “Tokyo Rose,” convicted 1949. Subsequently, pardoned by President Gerald Ford.
Mildred Gillars, also known as “Axis Sally”, convicted of treason on March 8, 1949; served 12 years of a 10- to 30-year prison sentence.
Tomoya Kawakita, sentenced to death for treason in 1952, but eventually released by President John F. Kennedy to be deported to Japan.
https://en.wikipedia.org/wiki/Category:People_executed_for_treason_by_country
Article 1, section 6
6: To provide for the Punishment of counterfeiting the Securities and current Coin of the United States;
Article 1, section 10
10: To define and punish Piracies and Felonies committed on the high Seas, and Offences against the Law of Nations;
Sure looks like Crimes Defined in the US Constitution to me.