Definition
Hostility is a legal term of art that operates differently depending on context. It carries distinct meanings in public international law, property law, employment law, and corporate law. The common thread is antagonism or opposition, but the legal content of that antagonism varies sharply by field.
1. International Law (Law of Nations). A state of open war between nations, or an act constituting open warfare. Hostility in this sense is a status concept — it describes the legal condition of belligerence between sovereign states — as well as an event concept describing individual acts of warfare. Bouvier distinguishes permanent hostility (attaching to citizens or subjects of a belligerent state by virtue of allegiance) from temporary hostility (attaching to individuals domiciled or resident in a belligerent state, which they may shed by removing themselves from that territory and renouncing the acquired national character).
2. Property Law — Adverse Possession. One of the required elements for a successful adverse possession claim. Hostility in this context does not mean ill will toward the true owner. It means the claimant's possession is without the owner's permission and inconsistent with the owner's title — i.e., the possessor asserts a claim of right. Some jurisdictions frame this as the claimant acting as if they owned the land; others require an actual subjective intent to claim ownership against the world. The permissive use of land (a license, for example) defeats hostility.
3. Employment Law — Hostile Work Environment. In discrimination law, hostility describes the quality of conduct sufficient to alter the terms or conditions of employment on the basis of a protected characteristic. The legal standard requires conduct severe or pervasive enough that a reasonable person would find the work environment abusive, combined with actual subjective perception of hostility by the plaintiff.
4. Corporate Law — Hostile Takeover. An acquisition attempt made without the approval or cooperation of the target company's board of directors. Hostility here is institutional, not personal — it refers to the absence of board consent, not necessarily to adversarial behavior between individuals.
Common Language
Modern common usage (Wiktionary): The state of being hostile; a hostile action, especially a military action.
Historical common usage (Webster's 1913): State of being hostile; public or private enemy; unfriendliness; animosity. Also: an act of an open enemy; a hostile deed.
The gap matters. In ordinary English, hostility connotes anger, enmity, or ill will toward another person. Legal usage across multiple fields has systematically stripped out this emotional content. In adverse possession, courts have repeatedly held that a claimant's friendly feelings toward a neighbor, or even ignorance that the land belongs to another, does not defeat the hostility element — what matters is the legal posture of the possession, not the possessor's state of mind. Researchers assuming the common meaning of hostility will misread the caselaw.
Common Confusion
Hostility vs. Claim of Right (Adverse Possession). Jurisdictions differ on whether hostility and claim of right are synonymous, overlapping, or distinct elements. In some states they are treated as a single inquiry; in others, claim of right adds a subjective intent requirement that hostility alone does not carry. Historical sources frequently use the terms interchangeably, which obscures real doctrinal differences in modern authority.
Hostility vs. Animus (International Law). Early treatise writers and the historical dictionaries use hostility to describe both a general state of war and specific hostile acts. Researchers should not assume that a reference to "hostility" in a 19th-century international law source connotes a formal declaration of war — hostility could attach to individuals or acts without a general state of war existing between sovereigns.
Recognized Forms
/SUBTYPES
Permanent Hostility (International Law): Hostility arising from citizenship or allegiance to a belligerent state. Not terminable by relocation.
Temporary Hostility (International Law): Hostility arising from domicile or residence in a belligerent state. Can be shed by departure and renunciation of the acquired national character.
Hostile Work Environment: The employment law subspecies, requiring severity or pervasiveness of discriminatory conduct, not mere unfriendliness.
Hostile Takeover: The corporate law subspecies, defined by absence of board approval, not by the conduct of the acquiring party.
Why It Matters in Research
This term is a research trap precisely because it looks familiar. Researchers entering the Law Mind corpus through international law materials will encounter a technically precise, state-of-war definition. If they carry that definition into property law searches, they will fundamentally misread adverse possession doctrine — courts have spent considerable effort explaining that hostility in adverse possession is a legal fiction, not a description of the claimant's emotional state or conduct.
The temporal dimension matters too. The international law meaning dominated the historical dictionaries because 18th- and 19th-century legal scholarship was preoccupied with the law of nations. The property law and employment law meanings are primarily 20th-century elaborations. Searching for "hostility" in materials predating roughly 1900 will return predominantly international law usage; post-1960 materials will skew heavily toward employment law and property law contexts.
The employment law hostile work environment doctrine developed almost entirely through federal anti-discrimination statute interpretation and is absent from the historical dictionaries entirely. Researchers using Black's or Bouvier's as a primary entry point will find no guidance on this usage.
For corporate law, "hostile" modifies "takeover" or "bid" as a compound term; searching for hostility alone in corporate law materials may not surface relevant results. Use the compound form.
Historical Dictionary Support
The five source dictionaries are in close agreement — unusual convergence — on the international law definition: hostility is a state of open war or an act of open warfare between nations. Burrill, Black's (both editions), and Bouvier all anchor to Kent's Commentaries for authority, indicating the historical legal understanding of hostility was essentially Kent's formulation applied through the 19th century.
Bouvier adds the most analytical content by distinguishing permanent from temporary hostility along lines of citizenship versus domicile. This distinction has modern relevance in international humanitarian law and conflict of laws analysis, though the terminology has evolved.
Rapalje & Lawrence is the thinnest of the five, essentially restating the open enmity formulation without elaboration.
What all five sources miss: the property law, employment law, and corporate law meanings. These contexts were not part of the 19th-century legal vocabulary for this term. Researchers should treat the historical dictionaries as authoritative on international law usage and as silent — not controlling — on every other modern context.
Jurisdictional Note
The adverse possession meaning of hostility varies by state, with some jurisdictions requiring a good-faith subjective belief of ownership, others requiring bad faith or conscious awareness that the land belongs to another, and still others adopting an objective standard indifferent to state of mind. Canadian and English adverse possession doctrine uses similar language but with different structural frameworks. The employment law hostile work environment doctrine is primarily federal in origin (Title VII) but has state law parallels with varying standards.
Encyclopedia Cross-Reference
Property Law Encyclopedia § property_85: Adverse Possession — Elements (Actual, Open, Notorious, Exclusive, Continuous, Hostile) — essential reading for the property law meaning of hostility, including the claim-of-right relationship.
Business Organizations & Corporate Law Encyclopedia § business_91: Mergers and Acquisitions — Hostile Takeovers and Defensive Measures — covers the corporate law usage and the board-approval framework that defines hostility in acquisition contexts.
Constitutional Law Encyclopedia § constitutional_99: Fighting Words, True Threats, and Hostile Audience — relevant to First Amendment doctrine where hostile audience response to speech triggers legal consequences; a distinct but related context where hostility has legal significance.