Definition
In law, "enemy" refers primarily to a nation engaged in armed conflict with another nation, and by extension to the citizens or subjects of that nation. The term carries distinct weight in international law, the law of war, property law, and constitutional law. Three overlapping senses appear across legal sources:
1. A hostile nation. A state against which another state has declared or is actively prosecuting war; the collective body of a belligerent power treated as a legal unit for purposes of international law.
2. An enemy individual (alien enemy). A citizen or subject of a nation at war with one's own country. Under this sense, an individual's legal status turns on national allegiance rather than personal hostility. An alien enemy may be subject to restrictions on contract, litigation, property ownership, and movement under domestic war statutes.
3. An enemy in service of a hostile power. Citizens or subjects of a neutral or friendly state who have joined or are actively aiding a belligerent nation. Anderson's formulation extends enemy status to persons seeking action from domestic government departments while owing allegiance to a hostile power.
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Common Language
Modern common usage (Wiktionary): Someone who is hostile to, feels hatred toward, or intends injury to another; also a hostile force or nation.
Historical common usage (Webster's 1913): One who hates and desires or attempts the injury of another; a foe or adversary. In military usage, "the enemy" referred to the hostile force collectively, construed as singular or plural.
The common meaning centers on personal animosity or opposition. The legal meaning is largely indifferent to personal feeling — an individual becomes an enemy in law by virtue of national allegiance at a time of declared or actual war, regardless of private sentiment. A German-born American resident who despised the Nazi regime could still qualify as an alien enemy under U.S. law during World War II. The gap between moral hostility and legal status is the critical distinction a researcher must hold in mind.
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Common Confusion
ENEMY vs. REBEL or INSURGENT: Anderson's entry expressly flags that "enemies of the United States" does not embrace rebels engaged in insurrection against their own government. This distinction was legally consequential during and after the American Civil War: Confederate combatants were treated as rebels (citizens in insurrection) rather than enemies in the international law sense, a classification with significant implications for treason prosecutions, property confiscation, and post-war legal status.
ENEMY vs. ENEMY COMBATANT: The modern term "enemy combatant" — prominent in post-September 11 detention law — derives from but is not identical to the classical "enemy" of the law of nations. The classical definition is rooted in state-versus-state war; enemy combatant doctrine has been applied to non-state actors and stateless persons, straining the traditional framework considerably.
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Why It Matters in Research
Researchers working in pre-twentieth-century sources will encounter "enemy" almost exclusively in its law-of-nations sense: state belligerency, prize law, and alien enemy property rules. The term's application to individuals in domestic legal proceedings accelerated sharply with World War I and World War II alien enemy legislation, and then again post-2001.
Key research traps:
First, the Civil War gap. Because Confederate participants were classified as rebels rather than enemies under international law, sources from 1861–1870 use "enemy" inconsistently. Some courts and writers applied the international-law framework by analogy; others refused to. A researcher cannot assume uniform usage in this period.
Second, alien enemy statutes. U.S. alien enemy statutes (rooted in the Alien Enemy Act of 1798) use the term with specific statutory meaning that may not align with either common usage or law-of-nations definitions. Corpus research touching on property sequestration, internment, or contract voiding during wartime must track the statutory definition operative in the relevant period.
Third, the enemy combatant evolution. Post-2001 executive and judicial materials repurposed the classical vocabulary of "enemy" in a non-traditional context. Constitutional Law Encyclopedia treatment is essential here; the classical dictionary sources are of limited direct use for understanding Hamdi, Boumediene, or Military Commissions Act provisions.
Fourth, Burrill's Latin hostis gloss is substantively useful. Burrill distinguishes hostis (public enemy, enemy of the state) from inimicus (private enemy, personal foe) — a classical Roman distinction that shaped common law treatment. Sources invoking hostis are invoking the public/international law sense; personal animosity is legally irrelevant.
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Historical Dictionary Support
The three source dictionaries are broadly consistent in defining enemy as a belligerent nation or its citizens, but each adds useful texture.
Bouvier offers the broadest individual-level extension, including citizens of friendly nations who have commenced or are preparing hostilities — capturing a kind of functional enemy status that goes beyond bare national allegiance. This formulation anticipates later terrorism-era debates about individual combatants outside formal state structures, though Bouvier did not contemplate that application.
Anderson is the most jurisdictionally specific, offering the "alien enemy" sub-definition with reference to domestic government dealings, and — critically — expressly excluding rebels from the enemy category. This exclusion was a contested legal point during Anderson's era and his precision here reflects genuine doctrinal awareness.
Burrill grounds the definition most firmly in the law of nations tradition, citing Kent's Commentaries and offering the Latin hostis to confirm the public-law register. Burrill's treatment is the most useful for prize law and international law research contexts.
None of the historical sources addresses non-state actors, stateless belligerents, or the constitutional due process dimensions that dominate modern enemy-status litigation. Researchers should treat these entries as authoritative for their period and as background architecture for modern doctrine — not as complete guides to contemporary law.
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Jurisdictional Note
The baseline definition of enemy for purposes of international law and war powers is federal in the United States, deriving from the law of nations and federal statute. State courts historically applied alien enemy rules in contract and property cases, and divergences existed. In British common law, the definition largely tracked the same law-of-nations framework, but specific statutory schemes (particularly during the World Wars) created distinct national regimes that should not be imported into American research without verification.
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Encyclopedia Cross-Reference
Enemy Combatant Detention — Hamdi, Boumediene, and Guantanamo (The Law Mind Constitutional Law Encyclopedia)
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