Definition
An alien enemy is a foreign national who, by virtue of owing allegiance — permanent or temporary — to a state or power with which the domestic sovereign is at war, acquires the legal status of an enemy. That status strips the individual of most civil capacities in the courts of the adverse belligerent for the duration of hostilities.
Two elements drive the definition: nationality (or allegiance) and the existence of a state of war. A subject or citizen of an enemy state becomes an alien enemy automatically upon the commencement of war, regardless of where that person is physically located. A person owing only temporary allegiance — such as a resident alien who happens to be domiciled in enemy territory when war breaks out — is treated as an alien enemy only for the period that temporary allegiance subsists; once it terminates, the hostile character terminates with it.
The primary legal consequence historically recognized is disability to sue: an alien enemy cannot maintain an action in the courts of the adverse belligerent. Rights may be restored only by the express license or favor of the sovereign (in English law, the Crown; in American law, executive authority).
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Common Confusion
ALIEN ENEMY should not be conflated with ENEMY COMBATANT, a post-World War II term that developed primarily in constitutional and military law contexts to describe individuals — including, potentially, citizens — subject to military detention or trial. Alien enemy is the older, civilian-law category focused on civil disabilities and property consequences. Enemy combatant is a status determination focused on military authority and due process rights. The two categories can overlap but operate under distinct legal frameworks. Researchers should also distinguish ALIEN ENEMY from ENEMY ALIEN, which is effectively a synonym but appears more frequently in 20th-century statutory usage, particularly in the Alien Enemy Act of 1798 (still codified in modified form at 50 U.S.C. §§ 21–24).
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Core Elements
The classical formulation requires:
1. ALIENAGE: The individual is not a citizen or subject of the domestic sovereign. A citizen of the belligerent's own nation cannot be an alien enemy under this doctrine, however disloyal.
2. ALLEGIANCE TO A HOSTILE POWER: The individual owes allegiance — permanent by birth or citizenship, or temporary by domicile or residence — to a state or power formally at war with the domestic sovereign.
3. STATE OF WAR: The doctrine applies in time of war. Historically, this meant declared or recognized armed conflict between sovereigns. Modern application raises difficult questions about undeclared conflicts and non-state actors.
4. DURATION: The disability attaches for the duration of hostilities (or the period of temporary allegiance, whichever is shorter) and generally lifts upon peace.
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Why It Matters in Research
This term carries significant research traps for anyone working across time periods.
The allegiance trigger matters more than domicile in the historical sources. Rapalje & Lawrence emphasize the practical context — alien enemies seeking relief from courts or seeking to participate in commerce during wartime — but the underlying doctrine turns on allegiance, not physical location. A researcher focused on early American or English cases must track whether the court was examining permanent versus temporary allegiance, because outcomes diverged sharply.
The civil disability to sue was not uniform and was subject to executive modification. The historical sources note that alien enemies could be granted special license to trade or litigate. This means that cases involving alien enemy plaintiffs in wartime are often decided on the threshold question of whether such a license existed, not on the merits. Researchers may find alien enemy pleas used as procedural weapons with little doctrinal development underneath.
The Alien Enemy Act of 1798 gives this term statutory grounding in American law that is frequently overlooked in private law research. That statute grants the executive broad power over alien enemies in wartime, including detention and deportation — powers that were exercised against Japanese, German, and Italian nationals during World War II and that have been invoked in 21st-century national security contexts. Researchers bridging common law doctrine and constitutional law must track this statutory dimension separately from the private law disability rules.
Property consequences are underexplored in the historical dictionary sources. At common law, alien enemy property was subject to confiscation or sequestration. The Trading with the Enemy Act (1917) and subsequent legislation layered a complex administrative and statutory framework over the common law baseline. Researchers working on property, trusts, or commercial law during either World War will need to move from the common law doctrine to the statutory scheme quickly.
Jurisdictional variation in the modern period is significant. Some states have their own alien property or trading-with-the-enemy statutes. Federal preemption questions arise frequently.
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Historical Dictionary Support
The four source dictionaries show strong agreement on the core definition and are essentially copying the same tradition, with Black's and Burrill's tracking each other closely and citing the same authorities (Coke on Littleton, Kent's Commentaries). This convergence reflects a stable classical doctrine rather than independent analysis.
Bouvier adds a nuance the others understate: the temporal character of the status. His formulation — that hostile character terminates when temporary allegiance terminates — is the most analytically precise of the four. This matters because it limits the doctrine's reach and has implications for how courts should treat individuals whose connection to the enemy power was contingent rather than national.
Rapalje & Lawrence offer the most practically grounded entry, noting the domicile context and the procedural reality that the term arose most often when someone was "seeking relief of some kind from our courts." This framing reveals that the doctrine was, in practice, a threshold defense raised in litigation rather than an affirmative power regularly exercised by the state.
All four sources are silent on the statutory framework, property sequestration, and the 20th-century executive detention dimensions. Researchers relying solely on these dictionaries will have an accurate picture of the civil disability rule but a dangerously incomplete picture of how the term actually operated in wartime legal practice.
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Jurisdictional Note
In the United States, federal law (the Alien Enemy Act, 50 U.S.C. §§ 21–24) controls the detention and removal dimensions of alien enemy status in wartime, and federal preemption substantially limits state law variation in that domain. The common law civil disability rule — barring alien enemies from suing — has been applied in American courts but its scope varies by state, and statutory modifications may apply. Researchers working outside the United States should note that English common law authorities cited in these historical dictionaries (particularly Coke and the early English reporters) reflect rules that were not always adopted wholesale in American jurisdictions.
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Encyclopedia Cross-Reference
Enemy Combatant Detention — Hamdi, Boumediene, and Guantanamo (The Law Mind Constitutional Law Encyclopedia)
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