Definition
A contract is a legally enforceable agreement between two or more competent parties, supported by sufficient consideration, in which each party undertakes to do or refrain from doing a particular thing. Where the agreement is broken, the law provides a remedy.
Four elements are conventionally required for a contract to be enforceable: (1) mutual assent (offer and acceptance), (2) consideration, (3) capacity of the parties, and (4) a lawful object. The absence of any element defeats enforceability, though the consequences differ by deficiency.
The term covers an enormous range of transactions — from a handshake sale of goods to a multi-party commercial financing arrangement — and the rules governing each vary considerably by type, subject matter, and jurisdiction.
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Common Language
Modern common usage (Wiktionary): "Contracted; affianced; betrothed. Not abstract; concrete." The everyday verb form — to contract a disease, to contract a debt — suggests acquiring or incurring something, often involuntarily.
Historical common usage (Webster's 1913): "To draw together or nearer; to reduce to a less compass; to shorten, narrow, or lessen... To bring on; to incur; to acquire; as, to contract a habit; to contract a debt; to contract a disease."
Editorial note: The common verb sense of "contracting" something (a disease, a habit) implies passive acquisition, even against one's will. The legal noun — a contract — is precisely the opposite: a voluntary, deliberate engagement requiring the active assent of competent parties. A researcher reading historical documents should not assume that the word "contract" in context refers to the legal instrument; writers of the 18th and 19th centuries freely used "contract" in the ordinary sense of incurring an obligation informally.
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Common Confusion
Contract vs. Agreement: In ordinary speech the terms are interchangeable. In law, every contract is an agreement, but not every agreement is a contract. An agreement lacking consideration, capacity, or a lawful object may be morally binding but not legally enforceable. Historical sources — including Bouvier and Anderson — sometimes use "agreement" and "contract" synonymously, which can mislead researchers into assuming enforceability where none exists.
Contract vs. Promise: A promise is unilateral; a contract requires mutuality of obligation (with exceptions for unilateral contracts). Early common-law sources blur this line, treating a promise under seal as enforceable on its own terms — a specialty or covenant — without the same consideration analysis applied to simple contracts.
Executed vs. Executory Contract: These terms describe the state of performance, not the formation of the contract. An executed contract is one fully performed on both sides; an executory contract has obligations remaining. The distinction matters enormously for remedies and for the effect of supervening events, but historical dictionaries sometimes treat these as categories of contracts rather than stages of a single contract's life.
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Core Elements
1. Mutual Assent. Offer by one party, acceptance by the other, on the same terms. The "meeting of the minds" formulation — prominent in 19th-century sources — has largely given way to an objective test: whether a reasonable person would understand that agreement was reached.
2. Consideration. Something of legal value given in exchange: an act, forbearance, or a return promise. Moral obligation and past consideration are generally insufficient at common law. The adequacy of consideration is ordinarily not weighed by courts; courts ask whether consideration exists, not whether it was a fair bargain.
3. Capacity. Parties must be legally competent — generally, of majority age and sound mind. Contracts with minors, persons adjudicated incompetent, or parties under duress or undue influence may be void or voidable depending on the deficiency.
4. Lawful Object. The purpose and subject matter must not be illegal, contrary to public policy, or otherwise prohibited. An agreement to commit a tort or crime is void.
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Recognized Forms
/SUBTYPES
Contracts of Record: Obligations recognized or established by a court — judgments, recognizances, statutes staple. These derive their force from the court's authority, not from the agreement of the parties, and are treated separately from consensual contracts in most historical analyses.
Specialty Contracts: Written contracts executed under seal. The seal historically supplied consideration by itself, making the question of independent consideration irrelevant. The legal significance of the seal has been abolished or substantially reduced in most U.S. jurisdictions.
Simple Contracts (Parol Contracts): All contracts not of record and not under seal, whether written or oral. The term "parol contract" in historical sources does not mean oral-only; it means not-under-seal. This is a persistent source of confusion in historical research.
Express Contracts: Terms stated explicitly by the parties, orally or in writing.
Implied Contracts: Terms inferred from the conduct of the parties or the circumstances. Courts further distinguish implied-in-fact contracts (genuine agreements inferred from conduct) from implied-in-law contracts (quasi-contracts), which are not true contracts at all but equitable remedies to prevent unjust enrichment.
Bilateral Contracts: Each party exchanges a promise for a promise.
Unilateral Contracts: One party promises performance in exchange for an act — acceptance occurs by completing the act, not by promising to do it.
Entire vs. Divisible Contracts: An entire contract requires complete performance before the other side's duty arises; a divisible contract can be apportioned, so partial performance on one side corresponds to partial obligation on the other.
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Why It Matters in Research
The word "contract" spans more than a millennium of legal development. Its meaning in a 13th-century source, a 1750 equity case, an 1870 treatise, and a 2020 commercial code commentary are related but not identical.
Seal doctrine is the most common trap. Pre-20th-century sources give sealed instruments — specialties — a fundamentally different legal treatment than unsealed ones. Consideration requirements, statutes of limitations, and merger rules all diverge between sealed and unsealed instruments in ways that have been substantially eliminated in modern law. Researchers reading 19th-century case law must identify whether the instrument at issue bore a seal before applying any rule stated in the opinion.
The parol evidence rule is a second trap. The rule restricts the introduction of extrinsic evidence to vary the terms of a written contract, but the rule's scope, exceptions, and underlying rationale have shifted materially across jurisdictions and over time. Researchers should not assume that a historical statement of the parol evidence rule maps cleanly onto modern doctrine.
Constitutional dimension: The Contracts Clause of the U.S. Constitution (Art. I, § 10) prohibits states from impairing the obligation of contracts. Cases arising under this clause involve a distinct body of law concerning what constitutes an "obligation" and what level of impairment is constitutionally tolerable. Researchers investigating legislation that modifies existing contracts must treat this as a separate inquiry from ordinary contract law.
Quasi-contract (implied-in-law) appears in historical digests alongside true contract doctrine. Bouvier and Black's 1st Ed. discuss these together in ways that modern doctrine does not. A remedy rooted in unjust enrichment — quantum meruit, quantum valebat — may appear indexed under "contract" in historical sources but operates on entirely different principles.
The Uniform Commercial Code (Article 2) governs contracts for the sale of goods in U.S. jurisdictions and displaces common-law rules on formation, modification, and gap-filling in significant respects. Historical common-law sources predate the UCC entirely and should not be used to state the modern rule for goods transactions without verification.
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Historical Dictionary Support
The major shelf dictionaries converge on the core definition: a contract is an agreement upon sufficient consideration between competent parties to do or refrain from doing a particular thing. Black's 1st Ed. draws from Blackstone (2 Bl. Comm. 442) and Kent (2 Kent, Comm. 449). Anderson's tracks the same lineage. Bouvier adds useful texture on executed vs. executory contracts, distinguishing completed transactions from those with remaining obligations — a distinction that remains analytically important.
Where the historical dictionaries diverge, or fall short, is on the classification of contracts. Black's 1st Ed. sets out the three-class taxonomy — contracts of record, specialties, and simple contracts — and expressly warns that "there is no such fourth class as contracts in writing" distinct from parol contracts. This was a live point of confusion in the 19th century and the dictionaries address it directly. Researchers working in this period should note that "written contract" is not a separate legal category at common law, only an evidentiary one.
Bouvier's treatment of construction principles points outward to specialized treatises — insurance policies, wills, deeds — acknowledging that contract construction is not a unified field but a set of overlapping and sometimes inconsistent doctrines by subject matter. This remains true. The historical dictionaries do not adequately treat the rise of standardized-form contracts or adhesion contracts, which generate a body of interpretive doctrine that postdates most of the shelf sources.
Rapalje & Lawrence's entry gestures toward the vendor-purchaser context and "open contracts" for land, illustrating that even within real property transactions, the baseline rules of contract construction shift by context. The shelf sources generally underrepresent the extent to which contract doctrine is domain-specific.
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Jurisdictional Note
All U.S. jurisdictions recognize the basic common-law framework of contract, but significant variation exists in the treatment of the seal, the scope of promissory estoppel as a substitute for consideration, the parol evidence rule's exceptions, and the implied covenant of good faith and fair dealing. Louisiana follows a civil-law tradition in which contract doctrine derives from the Civil Code rather than common-law precedent, producing material differences in formation and interpretation rules.
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Encyclopedia Cross-Reference
Law Mind Encyclopedia — Contract Law (comprehensive treatment of formation, interpretation, and breach)
Law Mind Encyclopedia — Consideration (doctrinal history and modern requirements)
Law Mind Encyclopedia — Contracts Clause (constitutional dimensions under Art. I, § 10)
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