A claimant's own carelessness rarely defeats a claim outright, but it can cut the award substantially. This chapter begins with the nature and statutory basis of the defence, who must prove it, and the two elements a defendant has to establish — including whether the claimant's fault must contribute to the accident or merely to the damage. It then examines the standard against which adults, children and intoxicated claimants are judged, and how courts fix the percentage reduction, including whether a 100% finding is ever possible. It closes with the recurring scenarios — seatbelts, drunk drivers and injured employees — and the distinctions between contributory negligence, volenti and failure to mitigate.