Definition
A third person is any individual or entity who is a stranger to a legal transaction, proceeding, or instrument — that is, someone who is neither a party nor in privity with a party. The term functions as a relational concept: it identifies a person by what they are not, rather than by a fixed legal status. Who qualifies as a "third person" shifts depending on the transaction or proceeding at issue.
Three principal contexts give the term most of its legal work:
1. Contract law. A third person is one who is not a party to a contract and did not furnish consideration for it. The significance here is whether that outsider may enforce the contract or be bound by it — the foundational question in third-party beneficiary doctrine.
2. Agency law. A third person is anyone with whom an agent deals on behalf of a principal. The agent and principal are the two parties; everyone else with whom they transact is the third person. Rights and liabilities between agents and third persons are a discrete body of law.
3. Procedure and evidence. A third person is a stranger to a lawsuit — neither a named party nor a privy — whose interests may nonetheless be affected by the outcome. Questions of standing, intervention, joinder, and collateral estoppel all hinge on whether someone qualifies as a third person relative to a given proceeding.
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Common Language
Modern common usage (Wiktionary): In grammar, "third person" refers to the set of verb forms and pronouns (he, she, it, they) used to refer to someone other than the speaker or the person addressed.
Historical common usage (Webster's 1913): The grammatical sense was well established by 1913 — third person in grammar denoted the party spoken of, as opposed to the first person (speaker) and second person (addressee).
The grammatical and legal senses share a structural intuition: both define "third person" by exclusion from a two-party relationship. But the legal term carries no grammatical content and should not be read through that lens. In legal sources, "third person" is always relational to a specific legal act — a contract, an agency relationship, a lawsuit — and the same individual may be a party in one proceeding and a third person in another.
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Common Confusion
THIRD PERSON vs. THIRD-PARTY BENEFICIARY: "Third person" is the broader category; a third-party beneficiary is a specific subtype. Not every third person has rights under a contract. A third-party beneficiary is a third person whom the contracting parties intended to benefit and who may therefore enforce the contract. Most third persons have no such rights. Researchers encountering "third person" in historical sources should not assume the source is addressing beneficiary rights unless that context is explicit.
THIRD PERSON vs. STRANGER: Older sources, including Bouvier's, use "stranger" as a near-synonym for third person. The terms are functionally interchangeable in most historical legal writing. Modern usage prefers "third party" in transactional and procedural contexts, while "third person" appears more frequently in property and tort discussions involving interference with legal relations.
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Why It Matters in Research
The term's relational nature is the primary research trap. Because "third person" is defined relative to a particular transaction or proceeding, the same individual can be a party in one context and a third person in another. Reading across cases or treatises without anchoring to the specific relationship at issue will produce confusion.
Terminology has shifted. Modern legal writing strongly favors "third party" over "third person." Historical sources — including Bouvier's and nineteenth-century treatises — use "third person" where contemporary materials would say "third party." When searching the Law Mind corpus in older materials, query both terms to avoid missing relevant passages.
The doctrine of privity amplifies the stakes. Whether someone qualifies as a third person (rather than a privy) historically determined whether they could sue or be sued on a contract. The erosion of strict privity rules in the twentieth century — particularly in tort and products liability — means that the legal consequences of being a "third person" have changed substantially. A source treating third persons as categorically excluded from contract rights may be stating law that has since been modified or reversed.
In agency materials, the third-person framing is structural. Agency law is essentially a three-party system: principal, agent, third person. The Law Mind Business Organizations & Corporate Law Encyclopedia entry on agent liability to third parties builds on this triadic structure. Researchers working through agency problems should understand that "third person" in that context is a term of art, not a casual description.
In tort materials, interference with contractual relations and related economic torts require identifying who is the third person relative to the contract being interfered with. The tortfeasor is by definition a third person to the contract; the analysis then turns on what duties, if any, run to or from that outsider.
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Historical Dictionary Support
Bouvier's Law Dictionary defines third person as "a person who is a stranger to a transaction or proceeding" and, equivalently, "one not a party or privy to a suit or instrument writing." Both formulations are negative definitions — the term describes an excluded status. Bouvier's also signals the contracts-for-the-benefit-of-third-persons doctrine, pointing toward the beneficiary question as the principal legal controversy attaching to this status.
The historical sources are consistent on the core meaning but thin on practical guidance. Bouvier's does not distinguish between the agency, contract, and procedural applications — a gap that matters in research because the consequences of third-person status differ significantly across those contexts. Modern encyclopedia and treatise materials are necessary to complete the picture.
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Jurisdictional Note
The term itself is not jurisdiction-specific, but the legal consequences of third-person status vary by state, particularly in contract law. Whether an intended third-party beneficiary can enforce a contract, and what showing is required to establish intended beneficiary status, differs across jurisdictions. Researchers should not assume that the general rule stated in any single historical source reflects current law in a particular state.
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Encyclopedia Cross-Reference
Agency — Liability of Agents to Third Parties (The Law Mind Business Organizations & Corporate Law Encyclopedia)
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