Definition
Reinsurance is a contract by which an insurer — having already issued a policy to an underlying policyholder — transfers all or part of that risk to a second insurer. The original insurer (the ceding company or cedent) pays a premium to the reinsurer in exchange for indemnification against losses arising from the original policy. The underlying policyholder is not a party to the reinsurance contract and ordinarily has no direct claim against the reinsurer.
Reinsurance serves two principal functions: it allows insurers to limit their exposure on any single risk or aggregate portfolio of risks, and it frees up capital that would otherwise be held in reserve against potential claims. In this sense, reinsurance is insurance of the insurer.
Two parties appear in every reinsurance relationship: the cedent (the original insurer, who assumes the role of "assured" in the reinsurance contract) and the reinsurer (who assumes the role of "insurer"). The underlying policyholder remains wholly outside this relationship. There is no privity of contract between the reinsurer and the original insured.
Common Language
Modern common usage (Wiktionary): Insurance purchased by insurance companies that spreads the risk associated with selling insurance around so the danger of one large monetary loss is minimized. Such insurance and catastrophe bonds are backstops to insurer insolvency from unexpectedly large losses.
Historical common usage (Webster's 1913): Insurance a second time or again; renewed insurance. A contract by which an insurer is insured wholly or in part against the risk he has incurred in insuring somebody else.
The common definitions capture the mechanics adequately. The legal gap worth noting is structural: laypeople may assume that reinsurance somehow extends or supplements coverage for the original policyholder, or that a policyholder can pursue the reinsurer directly on a loss. Neither is true at common law. The reinsurance contract is entirely between commercial parties in the insurance chain, and the absence of privity is a foundational legal principle, not a technicality.
Recognized Forms
/SUBTYPES
Treaty reinsurance: A standing agreement under which the reinsurer automatically accepts a defined class or portfolio of risks ceded by the cedent, without evaluating each risk individually. Treaty arrangements govern ongoing business relationships.
Facultative reinsurance: A case-by-case arrangement in which the cedent offers a specific risk and the reinsurer independently decides whether to accept it. Each placement is a separate negotiation and a separate contract.
Proportional reinsurance: The cedent and reinsurer share premiums and losses in an agreed proportion. Quota share and surplus share treaties are the principal proportional forms.
Excess of loss reinsurance: The reinsurer covers losses above a specified retention level, either per occurrence or in aggregate. This is the dominant non-proportional form and is standard for catastrophe protection.
Retrocession: A reinsurer itself purchases reinsurance, transferring risk it has already accepted from a cedent. The purchasing reinsurer is called the retrocedent; the accepting reinsurer is the retrocessionaire.
Why It Matters in Research
The central research trap is the privity gap. Historical cases and treatises consistently emphasize that the original insured has no direct right of action against the reinsurer unless a cut-through clause expressly grants one. Researchers working with older sources should be alert to jurisdictional variations on this point, as some courts have carved exceptions where an insurer becomes insolvent.
Terminology shifted significantly over the twentieth century. Early sources, including the historical dictionary entries below, use "reassurance" interchangeably with "reinsurance." Modern usage has standardized entirely on "reinsurance." Bouvier's formulation — that the cedent is the insurer in the original contract and the assured in the reinsurance contract — remains accurate and is a useful conceptual anchor when tracing older case law.
The "follow the fortunes" doctrine is a research node of particular importance. Under this doctrine, a reinsurer is bound to follow the cedent's good-faith coverage decisions, even if the reinsurer might have decided differently. This principle is not uniform across jurisdictions or contract forms, and its scope is heavily litigated. Researchers analyzing reinsurance disputes should treat "follow the fortunes" and "follow the settlements" as related but distinct concepts — the latter applies specifically to claims settlements, while the former is broader.
Arbitration clauses appear in the overwhelming majority of modern reinsurance contracts, which means that reported case law dramatically understates the volume of reinsurance disputes. Researchers relying solely on court decisions will miss the body of arbitration awards that shapes industry practice. Trade publications and secondary literature on arbitration panels are often more informative for current market practice than case reporters.
Regulatory treatment of reinsurance — particularly credit for reinsurance in statutory accounting — is a recurring research issue in insurance solvency and insurer insolvency proceedings. State insurance codes governing credit for reinsurance are not uniform, though model laws from the NAIC have produced substantial convergence since the 1990s.
Historical Dictionary Support
The three shelf sources converge on the core definition with useful precision. Black's (both editions) states the essential structure: an insurer procures a third person to insure it against loss or liability by reason of the original insurance. Black's 2nd edition attributes this formulation directly to California Civil Code § 2646, which is one of the earliest codifications of the concept in American law.
Bouvier's adds the most analytical detail of the three. It specifies that the reinsurance may cover all or part of the same risks, that the amount cannot exceed the original insurance, and — most usefully — it articulates the role reversal: the original insurer becomes the assured in the reinsurance contract. Bouvier's also makes the privity point explicit: "there is no privity of contract between" the reinsurer and the original insured. That observation remains black-letter law and is the starting point for understanding cut-through clause analysis.
None of the historical sources addresses the treaty/facultative distinction or the follow-the-fortunes doctrine, both of which are modern developments. Researchers should not expect shelf dictionary entries to resolve disputes involving these doctrines; those require case law, arbitral authority, and the specialist encyclopedia entries noted above.
Jurisdictional Note
Reinsurance is primarily governed by contract rather than statute, making the parties' agreement the first source of law in any dispute. Regulatory treatment — including requirements for collateral from unauthorized reinsurers and rules governing credit for reinsurance in statutory financial statements — varies by state, though NAIC model law adoption has narrowed these differences significantly. Some offshore reinsurance arrangements are governed by English law under Lloyd's market forms, and English reinsurance doctrine on issues such as utmost good faith and follow-the-settlements differs from prevailing American doctrine.
Encyclopedia Cross-Reference
Insurance Contracts -- Reinsurance and Risk Transfer (The Law Mind Contracts & Commercial Law Encyclopedia)
Reinsurance -- Treaty and Facultative, Follow the Fortunes, Cut-Through Clauses, and Arbitration (The Law Mind Insurance Law Encyclopedia)