Definition
A parol promise is an oral or unwritten promise that is not reduced to a formal written instrument. In classical contract law, the term also encompasses written simple contracts — that is, informal written agreements not made under seal — but its primary historical usage denotes a verbal undertaking to do or refrain from doing something.
The term operates at the intersection of two fundamental distinctions in contract law: (1) oral versus written agreements, and (2) simple contracts versus contracts under seal (specialty contracts). A parol promise stands in contrast to a covenant, which required a wax seal and formal execution to be enforceable at common law. Because a parol promise lacked that formality, its enforceability depended on the presence of consideration — the exchange element that distinguishes a binding contract from a mere gratuitous statement of intent.
Common Language
Modern common usage (Wiktionary): "Parol" as a standalone term is rarely used in ordinary modern English outside legal contexts. Where it appears, it refers generally to something spoken or oral.
Historical common usage (Webster's 1913): Webster's defines "parol" as "given or done by word of mouth; oral; also, given by a writing not under seal." Webster's further notes the legal sense: "parol evidence, oral evidence; evidence given by a witness by word of mouth."
The critical gap: Common usage collapses "parol" into simply meaning "spoken." Legal usage is more precise and more counterintuitive — a parol promise can be written, so long as it is not under seal. A researcher who assumes parol always means oral will misread historical sources discussing informal written agreements as if they were exclusively verbal transactions.
Common Confusion
PAROL PROMISE vs. PAROL EVIDENCE: These share a root and frequently appear in proximity, but they address different problems. A parol promise is the substantive legal act — the informal undertaking itself. Parol evidence refers to the rule of evidence that generally bars extrinsic evidence (including oral testimony) from varying or contradicting the terms of an integrated written agreement. Conflating the two leads to category errors in research: the parol evidence rule governs what evidence may be introduced at trial; a parol promise is what a party claims was made.
PAROL PROMISE vs. COVENANT: In early common law, these were sharply distinct. A covenant was a formal promise under seal, enforceable without proof of consideration. A parol promise required consideration and could not, at common law, be enforced by the writ of covenant. The distinction has substantially eroded in modern practice where seals have lost legal significance in most jurisdictions, but it remains essential when reading pre-twentieth-century cases and treatises.
Why It Matters in Research
Historical sources use "parol promise" in ways that can mislead researchers trained in modern contract vocabulary. Three traps to watch for:
First, the seal distinction was alive and consequential through much of the nineteenth century. When historical sources classify a promise as "parol," they are often making a point about formality and the availability of particular writs or remedies — not merely describing whether words were spoken aloud. Reading "parol promise" as simply "oral promise" will cause researchers to miss the procedural stakes.
Second, the Statute of Frauds creates a critical overlay. Many parol promises — even fully oral ones — became enforceable despite their informality once consideration was proved, but certain categories (sale of land, contracts not performable within a year, etc.) required written evidence under the Statute of Frauds. Historical sources sometimes use "parol promise" to signal that the Statute of Frauds question is lurking, even when the word "Frauds" never appears in the passage.
Third, employment law researchers should note the modern revival of parol promise doctrine in the context of implied employment contracts. Oral assurances of job security, made outside formal written agreements, are litigated today under reasoning that traces directly to the elements of parol promise enforceability — whether there was a definite promise, whether the employee relied on it, and whether consideration was exchanged. The Law Mind Employment & Labor Law Encyclopedia entry on breach of implied contract treats this lineage in detail.
Historical Dictionary Support
The three source dictionaries — Black's, Bouvier's, and Burrill's — are in near-total agreement, each defining a parol promise as "a simple contract; a verbal promise" and each citing Stephen's Commentaries (2 Steph. Com. 109) as the underlying authority. The alignment is notable: where dictionaries of this era often diverge on contested terms, the unanimity here reflects that the term was well-settled, not a site of doctrinal conflict.
What the historical dictionaries do not capture is the term's relationship to consideration doctrine, which was undergoing significant development during the same period these dictionaries were written. The definitions treat parol promise as descriptive (telling you what form the promise takes) without explaining why the form mattered (i.e., that seal-based enforceability was the alternative). Bouvier's entry on "Parol contract" — cross-referenced by Burrill — fills part of this gap and should be consulted alongside this definition.
Jurisdictional Note
The legal significance of the oral/written and parol/sealed distinctions has collapsed in most U.S. jurisdictions, where statutes have abolished or curtailed the common law effect of seals. The term "parol promise" itself rarely appears in modern American pleadings or opinions, having been absorbed into general contract vocabulary. Researchers working in English legal materials will encounter it with greater frequency and should apply the classical meaning with more care.
Encyclopedia Cross-Reference
The Law Mind Employment & Labor Law Encyclopedia: Breach of Implied Contract — Handbooks, Policies, and Promises