Definition
The act of forcing or constraining a person to perform an act they would not otherwise perform, whether through physical force, threats, or other forms of coercive pressure. In law, compulsion functions primarily as a doctrine that negates consent and, depending on context, may void obligations, excuse conduct, or support a defense to criminal liability.
Two distinct applications arise in legal usage:
1. Compulsion as a vitiating factor in contract and obligation: Acts performed under compulsion are generally not binding on the party compelled, because the consent required for a valid legal act is absent. The exception is significant: when lawful authority compels a party to do what they are already legally obligated to do — for example, when a court orders execution of a deed under threat of contempt — the compulsion does not taint the act. The obligation's validity stands because the underlying duty was legitimate and the compulsion was lawful.
2. Compulsion as a criminal defense: Compulsion may excuse otherwise criminal conduct when a person acts under an immediate threat of serious harm that leaves no reasonable alternative. This overlaps substantially with duress as a formal criminal defense doctrine.
Common Language
Modern common usage (Wiktionary): An irrational need or irresistible urge to perform some action, often despite negative consequences; also, the use of authority or power to force a person to act.
Historical common usage (Webster's 1913): The act of compelling, or the state of being compelled; the act of driving or urging by force or by physical or moral constraint; subjection to force.
The ordinary modern meaning has drifted toward the psychological — compulsion as an internal, often unwanted impulse (as in obsessive-compulsive disorder). The legal meaning runs in the opposite direction: compulsion is always external. It is a force or threat imposed from outside, not a drive arising from within. A researcher who encounters "compulsion" in a legal source should not read it through the psychological frame that dominates contemporary common usage.
Common Confusion
Compulsion, duress, coercion, and undue influence are frequently used interchangeably in both legal sources and secondary literature, but they carry distinct technical meanings across different bodies of law. Rapalje & Lawrence directs readers from COMPULSION to all three of these related terms, signaling that the historical profession treated them as a family rather than as synonyms. As a practical matter: duress is the most formalized doctrine in contract and criminal law; coercion tends to appear in criminal statutes and constitutional contexts; undue influence is the dominant concept in equity and probate; compulsion operates as the broadest umbrella term and the most natural description of the underlying factual condition. When reading historical sources, do not assume these terms are interchangeable — the choice of word often signals which body of doctrine the author is invoking.
Why It Matters in Research
The critical research trap with compulsion is the lawful/unlawful compulsion distinction, which historical sources treat inconsistently. Bouvier makes explicit what Black's leaves implicit: compulsion by lawful authority to perform an existing legal duty does not vitiate the act. This qualification is central to understanding historical contract disputes, equity proceedings, and cases involving court-ordered performance. A document executed under court order is not voidable merely because it was compelled.
The term also appears in constitutional research under the Fifth Amendment's self-incrimination clause ("nor shall be compelled in any criminal case to be a witness against himself"), where compulsion has its own specialized doctrinal development distinct from its contract-law or criminal-defense meanings. Researchers moving between constitutional and common-law sources should not carry definitions across without checking context.
In criminal law, compulsion as a defense is effectively the same doctrine as duress, but the preferred term varies by jurisdiction and era. Nineteenth-century sources lean toward compulsion; twentieth-century codifications generally use duress. When researching defenses in historical criminal records, search both terms.
The ecclesiastical procedure note in Black's (2nd ed.) — where a compulsory is a writ compelling witness attendance — is a discrete technical usage that modern researchers will rarely encounter except in pre-20th century English ecclesiastical court records or treatises. Flag it when it appears; do not conflate it with the substantive defense doctrine.
Historical Dictionary Support
Black's (both editions) defines compulsion tersely as "constraint; objective necessity. Forcible inducement to the commission of an act." The phrase "objective necessity" is worth pausing on: it signals that the historical legal understanding required the compulsion to be real and external, not merely subjective or self-imposed pressure.
Bouvier is the most analytically useful of the shelf sources here. He articulates the governing rule, the key exception (lawful authority compelling an existing duty), and implicitly distinguishes compulsion that vitiates consent from compulsion that does not. This remains a sound summary of the doctrine.
Rapalje & Lawrence decline to define the term independently and instead cross-reference coercion, duress, and undue influence — a structurally significant editorial choice suggesting that, by the late 19th century, compulsion was understood as the factual predicate shared across several distinct legal doctrines rather than as a freestanding doctrine of its own.
None of the shelf sources engages with constitutional compulsion (self-incrimination) or with the psychological sense that would come to dominate common usage in the 20th century. Researchers should not read backward from those absences.
Jurisdictional Note
The contours of compulsion as a criminal defense vary by jurisdiction in ways that matter. Some states codify it as a distinct defense; others subsume it entirely under duress. The threshold showing — immediacy of threat, severity of harm, absence of reasonable alternatives — is not uniform. Historical sources from English common law will not reliably map onto American state codifications.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Duress; Coercion; Consent and Its Vitiating Factors