Practice

The Marine Insurance Act includes, as a schedule, a standard policy (known as the 'SG form'), which parties were at liberty to use if they wished. Because each term in the policy had been tested through at least two centuries of judicial precedent, the policy was extremely thorough. However, it was also expressed in rather archaic terms. In 1991, the London market produced a new standard policy wording known as the MAR 91 form and using the Institute Clauses. The MAR form is simply a general statement of insurance; the Institute Clauses are used to set out the detail of the insurance cover. In practice, the policy document usually consists of the MAR form used as a cover, with the Clauses stapled to the inside. Typically each clause will be stamped, with the stamp overlapping both onto the inside cover and to other clauses; this practice is used to avoid the substitution or removal of clauses.
Because marine insurance is typically underwritten on a subscription basis, the MAR form begins: We, the Underwriters, agree to bind ourselves each for his own part and not one for another [...]. In legal terms, liability under the policy is several and not joint; i.e. The underwriters are all liable together, but only for their share or proportion of the risk. If one underwriter should default, the remainder is not liable to pick his share of the claim.