This chapter discusses the law on causation in fact. This is a matter of historical fact and can be addressed initially by the ‘but-for’ test. However, the but-for test is inadequate to establish causation in a number of different situations: unknown causes, cumulative causes, and consecutive causes and those in which the test produces an illogical or unjust outcome. It is an area in which recent policy-driven decisions have revived the approach of ‘material increase in risk’, as in the asbestos case of Fairchild v Glenhaven. Allocation of liability has been addressed in the Compensation Act 2006, s 3.