Definition
An implied contract is a legally enforceable agreement whose terms are not set out in explicit spoken or written words, but are instead inferred from the conduct, circumstances, acts, or relationship of the parties. The law treats the parties as having agreed, because their behavior reasonably indicates mutual assent and consideration even without a formal declaration.
Two distinct categories carry this name, and the distinction matters:
1. Implied-in-fact contract. A true contract arising from the parties' conduct rather than their words. The essential elements of contract — offer, acceptance, consideration, and mutual assent — are all present, but they are communicated through actions rather than express agreement. If you hand a mechanic your car keys and return three hours later to collect the repaired vehicle, no written contract was signed, but the law recognizes a binding implied-in-fact contract for reasonable compensation.
2. Implied-in-law contract (quasi-contract). Not a contract in any true sense. There is no actual agreement, express or implied, between the parties. Instead, the law imposes an obligation to prevent unjust enrichment — one party has received a benefit at another's expense under circumstances that make it inequitable to retain it without payment. The remedy is typically measured by the reasonable value of the benefit conferred (quantum meruit or quantum valebant), not by any bargained-for price.
Common Confusion
The term "implied contract" is frequently applied to both implied-in-fact and implied-in-law contracts as if they were the same thing. They are not. An implied-in-fact contract is a genuine contract — mutual assent exists, found in conduct rather than words. An implied-in-law contract (quasi-contract) is a legal fiction imposed by courts as an equitable remedy; no agreement exists at all. Conflating the two causes research errors because different rules govern formation, enforceability, the statute of frauds, and available remedies. Historical sources, including Black's and Burrill's, often use "implied contract" loosely to cover both. Later authority — particularly twentieth-century treatises and the Restatement (Second) of Contracts — works hard to separate them, reserving "quasi-contract" or "contract implied in law" for the unjust enrichment remedy and "contract implied in fact" for genuine-but-unspoken agreement.
Core Elements
For an implied-in-fact contract, courts generally require the same elements as any contract, established through conduct rather than words:
— Offer: One party's conduct signals a willingness to enter an agreement on ascertainable terms.
— Acceptance: The other party's conduct signals agreement to those terms.
— Consideration: Each party provides something of legal value.
— Mutual assent: The circumstances, taken together, indicate that both parties understood and agreed to the arrangement.
— Intent to contract: The parties must have acted under circumstances where a reasonable person would understand that an obligation was being undertaken.
For an implied-in-law contract (quasi-contract), the operative questions are not contract elements at all, but equitable ones: Was a benefit conferred? Was it accepted and retained? Would retention without compensation be unjust?
Why It Matters in Research
The implied-in-fact / implied-in-law divide is the single most important navigational issue for researchers working with this term. Before roughly the mid-nineteenth century, both concepts were routinely pleaded under common counts (indebitatus assumpsit) and discussed under the single heading of "implied contract." If you are reading pre-twentieth-century cases or treatises, you cannot assume which type of implied contract the court means without reading the underlying facts and remedy analysis closely.
In employment law, implied contract doctrine has expanded substantially in the modern era. Employee handbooks, personnel policies, oral assurances, and course-of-dealing can give rise to implied-in-fact employment contracts that limit an employer's at-will termination rights. This application is almost entirely absent from historical dictionary definitions, which reflect the classical commercial and service contexts. Researchers working in employment law should connect directly to the Law Mind Employment Encyclopedia entry on handbook and policy promises.
Statute of frauds issues arise distinctively here. An implied-in-fact contract is a real contract and may be subject to writing requirements if it falls within a covered category (real property, performance over one year, goods above a threshold value). An implied-in-law quasi-contract remedy is not a contract and generally escapes the statute of frauds — a research trap when the underlying transaction would otherwise require a writing.
Jurisdictional variation in how courts define and separate these two categories is significant enough to affect outcomes, particularly in employment, construction, and professional services litigation.
Historical Dictionary Support
Black's Law Dictionary captures the core classical definition cleanly: an implied contract is "one not created or evidenced by the explicit agreement of the parties, but inferred by the law, as a matter of reason and justice, from their acts or conduct," illustrating with the example of hiring someone to perform work. This definition runs together both the in-fact and in-law categories without drawing a clean line between them, which was typical of the period.
Burrill's entry is notably fuller and more analytical. Burrill ties the implied contract to natural justice and law's presumption of an undertaking to pay reasonable value — language that maps more onto quasi-contract than onto implied-in-fact contract as modern doctrine would distinguish them. His reference to "implied assumpsit" is historically useful: the common law action of assumpsit was the procedural vehicle through which both true implied contracts and quasi-contractual obligations were enforced, which explains why the categories blurred for so long. Burrill's citation to Blackstone's Commentaries (2 Bl. Com. 443; 3 Id. 158–165) points researchers to foundational source material worth consulting for the pre-modern framework.
Bouvier's entry, as preserved in the available source material, simply cross-references its main contract entry without independent elaboration — consistent with Bouvier's general practice of consolidating contract doctrine under a master entry.
What the historical dictionaries collectively miss: the employment context, the modern handbook doctrine, the Restatement's clean separation of quasi-contract from true contract, and the twentieth-century expansion of implied-in-fact contract in professional and relational settings.
Jurisdictional Note
Whether an employee handbook or employer policy creates an implied contract of employment varies significantly by state. Some jurisdictions readily find implied-in-fact employment contracts from handbook language; others require a clear and specific promise or apply a strong presumption of at-will employment that handbook disclaimers can preserve. Researchers should not treat any single jurisdiction's rule as general law.
Encyclopedia Cross-Reference
Contracts — Classification (Bilateral, Unilateral, Express, Implied, Quasi-Contract), The Law Mind Contracts & Commercial Law Encyclopedia
Breach of Implied Contract — Handbooks, Policies, and Promises, The Law Mind Employment & Labor Law Encyclopedia