Discrimination law prohibits direct discrimination, indirect discrimination and harassment, on protected grounds, such as race, sex, etc. Workers who use the legislation, or assist others to do so, need protection against retaliation by their employer. Accordingly, the legislation seeks to remove deterrents by creating a fourth instance of discrimination, known as victimisation. The statutory formula is sparse, apparently providing employers no defence. Yet in some cases, courts sympathetic to the employer have strained the formula to provide what amounts to a benign motive defence. The result is an incoherent body of case law. This article explores the problem in Britain, with some useful illustrations from the USA, and attempts to settle upon a new statutory formula that would provide certainty and clarity, as well as fulfilling the ambition of the anti-victimisation doctrine.