8.1 Insurance policies are contracts construed and enforced under the general rules of contract law. Historically, American courts followed English law on matters involving marine insurance. 2 In 1955, however, the United States Supreme Court decided the case ofWilburn Boat Co v.Fireman’s Fund Insurance Co, 3 wherein the court held that, absent a well-established federal maritime law, or a determination that the interests of national uniformity require that a rule of federal maritime law be fashioned, the interpretation of a marine insurance contract follows state law. In the United States, marine cargo insurance contracts are prepared by brokers, underwriters or their agents. For over a century, the American Institute of Marine Underwriters (“AIMU”), a trade association, has served the ocean marine insurance industry and has published Standard Cargo Clauses for the marine insurance market. 4 This chapter will address the construction of All Risks Cargo Clauses based on the application of well-established federal maritime law, supplemented by notable instances of the application of state law with a focus on New York law. As a preliminary matter, the chapter will consider the formation of a valid contract of marine insurance, starting with the assured’s duty to disclose all material facts concerning the risk. After examining these rules, there follows an analysis of: (1) the formalities that apply to marine insurance contracts; (2) open cargo policies; (3) certificates of insurance; (4) warranties; and (5) exclusions and other conditions.