Definition
An impossible contract is an agreement that the law will not enforce because one party cannot perform what was bargained for — the performance is either naturally impossible (physically incapable of being done by anyone) or legally impossible (prohibited by law or rendered unenforceable by operation of law). Because the consideration on which the promise rests cannot be delivered, the contract is treated as void or, where impossibility arises after formation, as discharged.
Two distinct situations fall under this heading:
1. Initial impossibility (void ab initio): The contract is impossible at the moment of formation. Neither party can be bound because the obligation never had a legal foundation — the consideration was illusory from the start.
2. Supervening impossibility: The contract was valid when formed but becomes impossible to perform due to a subsequent event — destruction of the subject matter, death of a necessary party, or intervening illegality. Here the contract is discharged rather than void.
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Common Confusion
IMPOSSIBLE CONTRACTS vs. IMPRACTICABILITY vs. FRUSTRATION OF PURPOSE: These three doctrines are frequently conflated, and the distinctions matter in a research context. Impossibility is the oldest and narrowest: performance must be objectively incapable of completion, not merely harder or more expensive. Commercial impracticability — codified in U.C.C. § 2-615 and adopted into the Restatement (Second) of Contracts — relaxes this standard, allowing discharge when performance remains technically possible but has become commercially unreasonable due to an unforeseeable contingency. Frustration of purpose is narrower in a different direction: the performance remains possible, but the underlying reason for the contract has been destroyed. Historical sources, including both editions of Black's, address only impossibility and may treat all three as variations of the same rule. Modern research must navigate this evolution carefully.
IMPOSSIBLE CONTRACTS vs. VOID CONTRACTS GENERALLY: Not every void contract involves impossibility. A contract void for illegality, lack of capacity, or mutual mistake is void on different grounds. The term "impossible contract" is specific to the performance-incapacity rationale.
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Core Elements
For a contract to be unenforceable on grounds of impossibility, courts historically required:
1. A valid contract at formation (or, for initial impossibility, an apparent contract whose defect defeats validity from the outset).
2. Performance that is objectively impossible — not merely difficult or unprofitable for this particular promisor, but impossible for anyone in the promisor's position.
3. The impossibility was not caused by the promisor's own fault or assumption of risk.
4. For supervening impossibility: an unforeseen event after contract formation that created the impossibility.
The objective/subjective distinction is critical. Early common law required strict objective impossibility. A promisor who found performance merely burdensome had no excuse. Modern doctrine has softened this through impracticability, but the historical authorities in this corpus — including the Wait treatise cited by Black's — apply the strict objective standard.
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Why It Matters in Research
This is a term with significant historical evolution that the corpus sources only partially capture. Both editions of Black's define impossible contracts through the lens of 19th-century common law — primarily the natural/legal impossibility binary drawn from Wait's Actions and Defenses. Researchers using these sources alone will encounter the strict classical framework and may miss the substantial doctrinal shift that occurred through the 20th century with the rise of commercial impracticability and the Restatement (Second).
Key navigational points:
The classical definition in Black's treats the void-ab-initio and supervening cases together without cleanly distinguishing them. Modern doctrine treats them differently, and researchers should be alert to which category a source or case is addressing.
The phrase "deemed void in the eye of the law" in Black's is doing heavy lifting. For initial impossibility, void is accurate. For supervening impossibility, modern courts prefer "discharged" — a meaningful distinction because discharge of a valid contract triggers restitution analysis, while a void contract raises different remedial questions. The encyclopedia entry on impossibility as a defense to equitable relief is particularly relevant here, since courts sitting in equity developed their own impossibility analysis somewhat independently of the common law contract rules.
Legal impossibility as a category requires care. Black's uses it to mean impossibility created by law — a contract to do something the law forbids. This is distinct from the criminal law use of "legal impossibility" as a defense to attempt liability, an entirely separate doctrine.
Researchers examining pre-20th-century cases will find "impossible contract" used as a general term for what modern law might parse as void for illegality, void for mistake, or discharged for impossibility. The historical sources do not always maintain these distinctions.
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Historical Dictionary Support
Both editions of Black's Law Dictionary reproduce nearly identical definitions, both crediting 7 Wait, Actions and Defenses 124 as authority. The consistency between editions suggests the editors did not regard this as a contested or evolving category in the period of publication — a sign that the doctrine was considered settled classical law, not yet disturbed by the commercial impracticability developments that would come later.
The Wait citation anchors the definition firmly in 19th-century treatise law. The core insight — that the impossibility of the consideration defeats the binding force of the promise — reflects the consideration-based architecture of classical contract law. If the exchange cannot occur, there is no enforceable bargain.
What the historical dictionaries do not address: the emergence of force majeure clauses as a contractual response to impossibility risks; the Uniform Commercial Code's codification of impracticability; or the Restatement (Second) of Contracts §§ 261–272, which restructured the entire impossibility/impracticability/frustration field. Researchers relying solely on Black's will have the foundation but not the subsequent development.
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Jurisdictional Note
The impossibility doctrine is broadly recognized across common law jurisdictions, but its scope varies. Some states have codified impracticability as an extension of impossibility (following U.C.C. Article 2 for goods contracts), while others maintain stricter traditional standards for services contracts. Civil law jurisdictions address analogous concepts through force majeure doctrine, which differs structurally from common law impossibility analysis.
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Encyclopedia Cross-Reference
Discharge — Impossibility of Performance (Objective Impossibility), The Law Mind Contracts & Commercial Law Encyclopedia.
Impossibility and Impracticability as Defenses to Equitable Relief, The Law Mind Remedies & Equity Encyclopedia.
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