27.1 In order to maintain the expected level of losses, marine insurance law and practice developed a range of rules to control the insured’s behaviour during the period when the underwriter is on risk. This chapter is concerned with those rules that restrict the insured’s ability to bring about losses by deliberate or reckless conduct. The application of the rules has been less frequent in war risks insurance, as marine risks underwriters are more likely to face “scuttling” losses and the like, but war risks underwriters have defended claims before the courts, and these are reviewed in this chapter.