Definition
A party is any person, entity, or group that has a recognized legal interest or role in a legal proceeding, transaction, or agreement. "Parties" is the plural form but is also used as a collective noun to describe all participants together.
The term operates across at least three distinct legal contexts:
1. Litigation: A party to a lawsuit is any person or entity formally named as a plaintiff (bringing the claim) or defendant (responding to the claim) in a legal proceeding. Third parties may be brought into litigation through joinder, intervention, or third-party claims. "Real party in interest" refers to the person whose rights are actually at stake, as distinguished from a nominal party.
2. Contracts and Transactions: A party to a contract or deed is any person or entity who enters into the agreement, incurs obligations under it, or receives rights from it. Contracts routinely use "party of the first part" and "party of the second part" as formal designations. In deeds and instruments, "party" and "parties" are used interchangeably regardless of whether the antecedent is singular or plural — a drafting convention noted in historical sources and still encountered in older instruments.
3. Statutes and Regulatory Proceedings: Statutes frequently define "party" specifically for their purposes, extending or limiting the ordinary meaning. Administrative proceedings have their own "party" designations, which may include intervenors, agencies, and affected persons who would not qualify as parties in a court action.
Common Language
Modern common usage (Wiktionary): A person or group of people forming one side of an agreement or dispute; also, a social gathering, or a political organization.
Historical common usage (Webster's 1913): "One of two or more persons who engage in a joint act or are jointly bound or affected by an act; one who is concerned or has an interest in an affair."
The ordinary sense of "party" correctly captures the idea of someone with a stake in an arrangement, but the legal meaning is more formal and consequential. Being a legal party confers specific rights (to notice, to be heard, to appeal) and imposes specific obligations (to respond, to comply with judgments or orders). A person deeply affected by litigation or a transaction may have a significant practical interest without being a legal party at all — and that distinction controls whether they are bound by a judgment or entitled to enforce a contract.
Recognized Forms
/SUBTYPES
— Plaintiff / Petitioner: The party initiating litigation.
— Defendant / Respondent: The party against whom a claim is brought.
— Third Party: A party brought into existing litigation by a defendant, or a person outside an original contract whose interests may nonetheless be affected.
— Real Party in Interest: The person whose substantive right is at stake, as distinguished from a nominal or procedural party.
— Party of Record: A party formally named in court documents, as distinguished from unnamed interested persons.
— Adverse Party: A party with interests opposed to another party in the same proceeding.
— Related Party: In tax and corporate law, a party with a defined relationship (family, ownership, control) to another, triggering special rules.
Why It Matters in Research
Party status is a threshold question in many areas of law, and researchers should approach the term with attention to context.
In procedural research, party status determines standing, the right to appeal, and whether a judgment is binding. A person who was not a party to a prior proceeding is generally not bound by its outcome — a rule with significant implications when researching res judicata and collateral estoppel doctrine.
In contract research, the distinction between parties and third-party beneficiaries is critical. Only parties can enforce a contract as a matter of right under classical common law doctrine; third-party beneficiaries occupy a different and historically contested position. Researchers working in older materials should expect that the enforceability of third-party rights was not settled law for much of the nineteenth century.
In deed and instrument research, historical sources — including Bouvier's — note that "party" and "parties" were used interchangeably in drafting regardless of grammatical number. Researchers reviewing old deeds, mortgages, or conveyances should not read "parties" as implying plurality when the context suggests a single grantor or grantee.
In tax and corporate research, "related party" carries a technical meaning defined by statute and regulation. The ordinary legal sense of "party to a transaction" is not equivalent to "related party" under the Internal Revenue Code or securities regulations — conflating the two leads to research errors.
The corpus spans multiple centuries and jurisdictions. Statutory definitions of "party" in administrative, procedural, and regulatory codes vary significantly. Never assume that a definition from one statutory scheme governs another.
Historical Dictionary Support
Bouvier's entry for "party" is minimal, noting primarily the drafting convention that "party" and "parties" are used interchangeably in deeds without regard to singular or plural antecedents. This reflects a practical observation about instrument drafting rather than a substantive legal definition, and it is the kind of granular note that proves useful when parsing old conveyancing documents.
Bouvier's broader corpus treats "party" as a foundational procedural concept — someone who has a direct interest in the subject of litigation or a transaction — but does not develop the constitutional or statutory dimensions that later became important. Researchers should note that nineteenth-century treatises generally did not distinguish sharply between parties and third-party beneficiaries in contract, or between parties and intervenors in procedure, in the way modern doctrine does. The modern elaborations (real party in interest requirements, standing doctrine, administrative party status) are largely twentieth-century developments not captured in historical dictionary sources.
Jurisdictional Note
The core meaning of "party" in litigation and contract is consistent across American jurisdictions, but statutory definitions vary. Federal procedural rules (Rule 17, Federal Rules of Civil Procedure) impose a real-party-in-interest requirement with specific content; state procedural rules differ. Administrative law "party" definitions are jurisdiction- and agency-specific. Researchers should always check the operative definition in the relevant procedural or statutory scheme.
Encyclopedia Cross-Reference
— Novation — Substitution of Parties (The Law Mind Contracts & Commercial Law Encyclopedia): Directly addresses how party status changes through novation, including the legal effect of substituting a new party for an original one.
— Related Party Transactions (The Law Mind Tax Encyclopedia): Covers the technical "related party" definition and its consequences in tax law — a distinct but frequently encountered use of party terminology.
— Agency — Liability of Agents to Third Parties (The Law Mind Business Organizations & Corporate Law Encyclopedia): Addresses the boundary between parties and third parties in agency relationships, including when an agent or principal is a party to an agreement versus a disclosed or undisclosed non-party.