This chapter will present a representative sampling of eighteenth-and nineteenthcentury decisions of English and US courts which involved judicial deliberation upon intervening causation issues. As we shall see, up until at least the mid-nineteenth century, the courts were wary of unduly restricting the defendant’s liability which would otherwise occur were they to recognise too readily the severance of the causal chain by a novus actus. This the courts did by applying the Polemis-like ‘direct consequence’ test1 in England and the ‘proximate cause’ formula in the United States. In Milwaukee and St Paul Railway Company v Kellogg2 the United States Supreme Court stated that the proximate cause of a plaintiff’s injury may still be attributable to the defendant’s negligence even though such injury operated through successive agencies, so long as that injury was the ‘natural and probable consequence’ of that negligence.3 Gradually, however, the courts of both countries relaxed the rigorous application of these tests such that novus actus pleas enjoyed more success as the nineteenth century ended.