Definition
High treason is the most serious category of treason — an offense committed against the sovereign, the state, or the supreme authority of the realm, as distinguished from lesser forms of treason directed against private persons. In historical English law, the distinction mattered because treason could theoretically be committed at two levels: against the king (high treason) and against certain private superiors — a servant against a master, a wife against her husband, a religious person against a prelate (petit treason). High treason occupied the apex of that hierarchy.
In modern usage, the qualifier "high" has lost its operative significance. After petit treason was abolished by 9 Geo. IV. c. 31, § 2 (1828), there was no longer a lesser category of treason to contrast against. The term "high treason" survives primarily as a rhetorical intensifier and as a historical designation. Contemporary statutes and legal commentators in England and most common law jurisdictions simply say "treason."
In American law, the distinction between high and petit treason was never formally adopted. The U.S. Constitution defines treason in Article III, Section 3 without reference to degree, and federal statute (18 U.S.C. § 2381) follows suit. "High treason" appears in American legal literature almost exclusively in historical or comparative contexts.
Common Language
Modern common usage (Wiktionary): Criminal disloyalty to one's country or sovereign; in some jurisdictions, treason with aggravating features; colloquially, a betrayal portrayed as especially shocking.
Historical common usage (Webster's 1913): Treason against the king or government, as distinguished from petit treason.
The common use of "high treason" as a dramatic intensifier — suggesting any severe betrayal — has drifted far from the term's original legal function. Legally, "high" was not an adjective of degree indicating worse treason; it was a categorical marker distinguishing sovereign-directed offenses from subject-directed ones. A researcher encountering "high treason" in popular or political writing should not assume the speaker is invoking the technical distinction. The rhetorical use is now the dominant one.
Common Confusion
High Treason vs. Treason: These terms are not synonymous in historical sources, though they are treated as synonymous in modern ones. In pre-1828 English law, high treason and treason were overlapping but not identical concepts — treason was the broader category, high treason the specific branch directed at the sovereign. After the abolition of petit treason, the terms converged. Researchers working with sources before the mid-nineteenth century should not assume the two terms are interchangeable.
High Treason vs. Petit Treason: Petit treason (sometimes "petty treason") was a now-abolished offense covering betrayal within certain private hierarchies — servant to master, wife to husband, clergyman to prelate. It was formally a species of treason but carried distinct procedural and punitive consequences. The abolition of petit treason in 1828 is what rendered "high" in high treason redundant. See PETIT TREASON.
Why It Matters in Research
The central research trap is chronological. Sources before 1828 use "high treason" as a term of art with specific legal content. Sources after 1828 use it loosely, if at all. A researcher reading a seventeenth- or eighteenth-century English authority must recognize that "high treason" is not merely emphatic language — it is placing the offense in the upper tier of a two-tier system with different courts, procedures, and penalties.
In American historical sources, the term appears frequently in the colonial and founding periods, often imported from English legal vocabulary without the accompanying doctrinal framework. American courts and legislators did not inherit the petit/high treason bifurcation, so encounters with "high treason" in early American materials are often rhetorical or reflect English legal education rather than operative American doctrine.
Corpus researchers should also note that Black's Law Dictionary's entry, as reported here, is incomplete — it cuts off mid-sentence ("Treason against the king or sovereign, as"). This suggests the entry was excerpted from a longer treatment of TREASON, where the full doctrinal discussion likely resides. Researchers using Black's for this term should turn directly to the TREASON entry for substantive content.
The Statute of Treasons (25 Edw. III, St. 5, c. 2, 1351) is the foundational English source for what acts constituted high treason. That statute — levying war against the king, adhering to his enemies, compassing the king's death, and related acts — remained the backbone of English treason law for centuries and is the document against which historical sources should be read.
Historical Dictionary Support
The four source dictionaries agree on the core definition: high treason is treason against the sovereign, distinguished from petit treason against a private superior. Rapalje & Lawrence and Burrill's both note the post-1828 obsolescence of the qualifier "high" with some precision — Rapalje & Lawrence observe it is "not now usually retained" and Burrill's notes that Stephen omitted the term from his New Commentaries on this ground. Bouvier's provides the most complete enumeration of what petit treason covered (servant/master, wife/husband, religious/prelate) without adding doctrinal depth on the high treason side. Black's entry, as available here, is truncated and offers less than the others.
None of the four dictionaries engages substantively with the American treatment of high treason or with the 1351 Statute of Treasons as the operative historical foundation. Researchers should not rely on these entries for the English statutory history — Blackstone's Commentaries (4 Bl. Com. 74–92) and the statute itself are the necessary primary sources, and Burrill's citation to 4 Bl. Com. 74–75 is the dictionary shelf's most useful pointer in that direction.
Jurisdictional Note
In England and Wales, the relevant modern statute is the Treason Act 1351 as amended, with subsequent modifications. The term "high treason" no longer appears in operative statutory language. In the United States, treason is defined constitutionally (Art. III, § 3) and federally (18 U.S.C. § 2381); "high treason" has no statutory status. Some Commonwealth jurisdictions retain the phrase in older statutes not yet consolidated.