How does the US Constitution define treason and what are the penalties?

1. The Constitutional definition: a deliberately narrow, historically rooted crime

The Constitution places the sole definition of treason in Article III, Section 3: treason “shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort,” language taken from English statutory tradition but sharply narrowed to prevent political abuse ^{[1] [4]}. Legal commentary and the Constitution Center stress the Framers deliberately rejected broader English doctrines—such as prosecuting mere speech or imagined plots—to avoid turning political opposition into capital crimes ^{[4] [6]}.

2. Proof: a built‑in evidentiary safeguard

Article III adds procedural protections: “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,” creating a high hurdle for conviction that courts have taken seriously as a structural check on prosecutions ^{[1] [5]}. Court decisions and scholarly summaries discuss how the two‑witness rule raised the bar and that the requirement reflects the Framers’ fear of treason charges being used for political ends ^{[5] [6]}.

3. What “levying war” and “aid and comfort” have meant in practice

Courts have read “levying war” to require an actual assemblage for a treasonable, forceful purpose—mere conspiracies or remote support without an actual levying of war do not automatically qualify ^{[7] [8]}. “Adhering to their Enemies” or giving “aid and comfort” has been treated as requiring intent and concrete assistance to a recognized enemy; speech or unpopular political actions absent an intent to betray usually do not satisfy the constitutional definition ^{[6] [9]}.

4. Federal penalties set by Congress: death, long prison terms, fines, and disqualification

While the Constitution leaves punishment to Congress, statutory law prescribes severe penalties: under 18 U.S.C. §2381, a convicted traitor “shall suffer death, or shall be imprisoned not less than five years and fined … not less than $10,000,” and be ineligible to hold federal office—language reproduced in legal summaries and the official U.S. Code digest ^{[2] [3] [10]}. Historical notes in the sources show treason prosecutions since 1789 have been rare, reflecting the clause’s narrow scope ^{[9] [10]}.

5. Historical practice: rarity and caution in prosecutions

Because of the Constitution’s narrow definition and proof requirements, treason prosecutions at the federal level are uncommon—sources count only a few dozen trials since the founding and few convictions—underscoring that the Framers’ safeguards have had practical effect ^{[9] [10]}. Scholarship and annotations stress the Framers’ desire to avoid the English pattern where treason charges suppressed dissent ^{[4] [11]}.

6. Limits, ambiguities, and contemporary debates

Legal commentators note persistent questions: how to apply “levying war” when actions fall short of classical battlefield assemblages, the reach of “aid and comfort” into modern contexts, and how the two‑witness rule interacts with contemporary evidence types; courts have struggled with these issues in a handful of cases ^{[7] [5] [6]}. Sources also make clear that other statutes address related conduct (e.g., seditious conspiracy, espionage) and have been used more often than constitutional treason charges ^{[9] [10]}.

7. What the sources do not say / gaps in reporting

Available sources do not mention any recent change to the statutory penalties beyond 18 U.S.C. §2381, nor do they provide exhaustive lists of every treason prosecution or case law developments after the cited analyses ^{[2] [10]}. For specific contemporary applications or pending litigation, consult up‑to‑date court filings and primary statutes beyond these summaries.

Conclusion: The Constitution narrowly defines treason and shields defendants with high proof requirements; Congress prescribes severe punishments (including death, long terms, fines, and disqualification from office) but treason prosecutions have remained rare because of the clause’s restrictive language and evidentiary safeguards ^{[1] [2] [9]}.