Definition
A clause appearing in marine insurance policies that causes the contract to relate back to the inception of a voyage already underway—or to some other specified antecedent moment—so that the policy is valid and effective even if, at the time of execution, the insured vessel or cargo has already perished or suffered loss from a covered peril. The clause operates prospectively and retrospectively at once: it insures against risks not yet known to have materialized, while simultaneously covering losses that may already have occurred at the moment the ink dries.
The animating principle is good faith. The clause is enforceable only when neither party has knowledge of the outcome at the time the policy is executed. If the vessel is already known to be lost by either the insurer or the assured, the clause does not save the policy—fraud or concealment voids coverage entirely. If neither party knows, the risk is genuinely mutual and the contract stands. If the assured alone knows of the loss, the policy is void against the insurer; if the insurer alone knows the vessel is safe, the assured may hold the insurer to the contract.
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Common Language
Modern common usage (Wiktionary): "Lost" means no longer in one's possession or unable to be found. "Not lost" is simply its negation.
Historical common usage (Webster's 1913): "Lost" — parted with; ruined or destroyed; no longer possessed. The word carries finality and certainty in ordinary speech.
The legal gap here is significant. In ordinary language, "lost or not lost" would be a redundant or even absurd phrase—something is either lost or it isn't. In marine insurance, the phrase is a term of art that deliberately embraces uncertainty, covering both possible states simultaneously at the moment of contracting. The legal meaning is not about ambiguity or carelessness; it is a precise device for allocating risk across time when the parties are ignorant of current facts.
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Common Confusion
The clause is sometimes confused with a general waiver of the insurer's defenses or with a retroactive endorsement. It is neither. It does not cure concealment, misrepresentation, or fraud. It does not allow a party with actual knowledge of the loss to collect—courts have consistently held that the mutual ignorance requirement is the clause's load-bearing condition. Researchers should also distinguish this clause from a "lost profits" provision, which appears in commercial contracts and insurance policies in entirely different contexts.
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Why It Matters in Research
This term is narrow in application but important in historical commercial law research. It appears almost exclusively in marine insurance instruments, and its prevalence tracks the age of sail—policies written before rapid communication made real-time vessel status knowable. Researchers working in admiralty, maritime commerce, or early insurance law will encounter it frequently in printed policy forms, insurance litigation records, and treatise discussions of marine insurance practice from roughly the seventeenth through the nineteenth centuries.
Several research traps apply. First, the phrase appears as a single unit of meaning—neither word carries independent legal weight in this context. Indexing and searching on "lost" alone will not surface the clause reliably. Second, historical sources often discuss the clause in the context of good faith obligations and the duty of disclosure, so researchers following the thread of uberrimae fidei (utmost good faith) doctrine will find relevant material there. Third, Burrill and Black both treat the clause briefly, leaving the doctrinal substance to treatise literature on marine insurance—particularly Arnould on Marine Insurance and, in the American tradition, Duer's treatise on insurance—which remain the authoritative sources for the clause's contours.
The clause also has a procedural dimension that research may miss: in early English and American cases, disputes about the clause frequently turned on what counted as "knowledge" at the moment of contracting, drawing in evidence law questions about notice, agency, and imputed knowledge. Researchers interested in the epistemological foundations of insurance law will find the clause a productive entry point.
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Historical Dictionary Support
Black's Law Dictionary identifies the clause with precision: it is inserted in marine policies to signify that the contract relates back to the beginning of a voyage in progress or to another antecedent time, and it remains valid even if the vessel has already perished, provided neither party has knowledge of the loss. This matches the standard commercial practice described in Burrill, who places the clause in commercial law and identifies it as a standard marine insurance device. The two sources agree on function and scope.
Both sources are sparse on the doctrinal elaboration—neither Black's nor Burrill develops the good faith conditions at length. Researchers should treat these entries as identification aids rather than complete legal analyses. The significant doctrinal development of the clause's mutual-ignorance requirement, and the consequences of unilateral knowledge, is largely absent from general law dictionaries and must be pursued in insurance-specific treatises and case reporters.
Neither dictionary addresses the clause's declining practical importance as telegraphy and later instantaneous communication eliminated the information gap that gave the clause its commercial rationale. By the late nineteenth century, the clause was increasingly a formality in many maritime markets, retained more by drafting convention than operational necessity.
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Jurisdictional Note
The clause originated in English marine insurance practice and was transplanted into American commercial usage largely intact. Its interpretation follows admiralty and maritime law principles, which in the United States are federal in character. Significant variations in the clause's treatment are more likely to appear across historical periods than across domestic jurisdictions.
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Encyclopedia Cross-Reference
The Law Mind Property Law Encyclopedia: Personal Property — Acquisition by Find (Lost, Mislaid, Abandoned, Treasure Trove) [property_132] — Relevant only for researchers who encounter "lost" in a property law context and need to distinguish that usage from the marine insurance clause.
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