Definition
A Latin term from the law of war meaning a hostage — a person delivered to an enemy or opposing party as a pledge or security for the performance of a treaty, agreement, or other obligation. The plural form is obsides. The term appears in classical legal texts treating the conduct of war and the obligations arising from treaties between sovereign powers.
Common Confusion
OBSES and OBSIDES (or OBSIDES) are sometimes treated as distinct entries in older legal glossaries, but they are simply singular and plural of the same term. Separately, researchers should not conflate OBSES with OBSESSIO, a distinct Latin legal term referring to a siege or blockade — an entirely different concept in the law of war.
Why It Matters in Research
OBSES is a term researchers encounter almost exclusively in Latin legal texts and early modern treatises on the law of nations, not in primary legal sources from common law jurisdictions. Its practical significance is limited to two research contexts: (1) historical international law, particularly works in the Grotian tradition addressing the law of war, and (2) diplomatic history touching on treaty guarantees enforced through the delivery of persons.
The term does not appear in domestic common law case law or statutes with any frequency. Researchers working in early American or English legal archives will not find OBSES functioning as operative legal language; they will find HOSTAGE instead. OBSES surfaces in legal dictionaries primarily because those dictionaries aimed to serve readers of Latin treatises, not practitioners.
The Burrill citation to Grotius's De Jure Belli ac Pacis (lib. 3, c. 20, § 52) and to Magna Carta (Johann's charter, c. 49) is the most useful navigational pointer in the historical record. Magna Carta chapter 49 required King John to return hostages taken from barons — a provision using the vernacular and Latin equivalent — and Grotius's treatment of obsides in Book III is the definitive early modern analysis of the legal status, rights, and treatment of hostages under the law of nations. Researchers tracing the international law of hostages should treat these two sources as the primary anchors.
Historical Dictionary Support
All three source dictionaries agree completely: OBSES means hostage in the law of war, with the plural OBSIDES. The entries are nearly identical, reflecting a shared dependence on the same Latin legal tradition rather than any independent analysis. The 2nd edition of Black's contains a typographical error ("Obdsides") that carries no legal significance.
Burrill's entry is the most useful of the three because it provides citations — to Grotius and to Magna Carta — that the Black's editions omit. This is characteristic of Burrill's approach: his dictionary, aimed at practitioners and scholars working with primary sources, more often identifies the underlying authority.
None of the three dictionaries address the legal status of the obses in any depth: whether the hostage bore personal liability, what happened upon the principal party's breach, or how the practice evolved and eventually fell into disuse under modern international law. Researchers seeking that analysis must go directly to Grotius or to later treatises on the law of nations such as Vattel's Le Droit des Gens.
The Latin dictionary source confirms the classical usage: obses derives from obsedeo and carries the core meaning of a person given as a pledge or security, with the paradigmatic construction "obsides accipere" (to receive hostages) versus "obsides dare" (to give hostages), reflecting the power dynamic between parties.