Definition
Latin plural of *hostis*. In classical Roman and received English legal usage, *hostes* means public enemies — specifically, those against whom war has been formally declared, or who have formally declared war, on a public (state) basis. The term carries two related but distinct applications in legal sources:
1. PUBLIC ENEMIES (general sense): Persons or peoples standing in a declared state of war with a sovereign. Under Roman civil law doctrine adopted into English legal writing, *hostes* are distinguished from mere pirates or robbers by the public, state-sanctioned character of the hostility. A nation's acknowledged wartime adversary is a *hostis*; a brigand acting without state authority is not.
2. HOSTES HUMANI GENERIS (enemies of the human race): A derived phrase designating pirates specifically. Because pirates prey on all nations indiscriminately and operate outside any sovereign's authority or protection, they were treated by law as enemies of all mankind — subject to capture and punishment by any nation, without the procedural protections normally extended to enemy combatants in declared war.
Common Confusion
*Hostes* and *pirates* operate in close proximity in legal literature, and the relationship between the two concepts can mislead researchers. The categories are legally opposed, not synonymous. *Hostes* in the primary sense are public enemies recognized by law of nations — they have rights under the law of war. Pirates, designated *hostes humani generis*, are emphatically excluded from that category: they hold no sovereign authority, no flag protects them, and any nation may proceed against them. The phrase *hostes humani generis* uses *hostes* metaphorically to convey universal enmity, but it simultaneously strips pirates of the legal standing that genuine *hostes* possess. Conflating the two distorts both the law of war and the law of piracy.
Why It Matters in Research
Researchers encounter *hostes* in three distinct legal contexts, and the context governs which meaning controls.
First, in law of nations and prize law sources, *hostes* marks the boundary between lawful belligerency and outlawry. The Roman law definition — enemies are those against whom war is publicly declared; all others are pirates or robbers — was carried forward through Grotius, Vattel, and into Blackstone and American prize court jurisprudence. When reading 18th- and 19th-century admiralty and international law sources, a researcher must identify which sense is operative: the recognized public enemy or the outlaw.
Second, the phrase *hostes humani generis* became a foundational concept in Anglo-American piracy law and persists into modern international law. It grounds universal jurisdiction over piracy — the doctrine that any state may try a pirate regardless of where the offense occurred or the nationality of victims. Researchers tracing universal jurisdiction doctrine will find *hostes humani generis* as an early doctrinal anchor.
Third, historical sources diverge in how carefully they handle the Roman law source. Burrill flags that Blackstone quoted the Digest accurately while Coke did not — a caution worth heeding when tracing the definition through common law commentaries. Imprecise quotation of the underlying civil law maxim produced some doctrinal slippage in English authorities.
The term appears almost exclusively in Latin in historical sources. Full-text corpus searches should include both *hostes* and *hostis* (the singular nominative), as well as the compound phrase *hostes humani generis*, to capture the full range of usage.
Historical Dictionary Support
The four source dictionaries present a consistent picture with one notable divergence in analytical depth.
Black's (both editions) and Bouvier treat *hostes* briefly — translating it as "enemies" and glossing *hostes humani generis* as pirates, without elaboration. These entries function as cross-references rather than substantive treatments.
Burrill provides the most analytically complete entry. He quotes the Digest directly (Dig. 50.16.118) and supplies the civil law definition in full: the distinction between public enemies and pirates/robbers turns on the public, declared character of the war. He also provides the secondary Digest citation (Dig. 49.15.24) and, critically, notes the discrepancy between Blackstone's accurate rendering and Coke's careless quotation of the same maxim. This is the entry most useful for understanding the doctrinal genealogy.
What the historical dictionaries collectively omit is any treatment of how *hostes humani generis* evolved from a Roman law categorization into a jurisdictional doctrine in Anglo-American admiralty law. Researchers should supplement these entries with primary admiralty sources and international law treatises for that development.
Jurisdictional Note
*Hostes* and *hostes humani generis* are law of nations concepts, not creatures of any single domestic legal system. Their application in prize law and piracy prosecutions was broadly shared across English and American admiralty courts, though the specific procedural consequences — who could try pirates, what procedures applied — varied by domestic statute and treaty.