P wasn’t wearing a seat belt and D, by his own fault, caused a car crash with P. P would not have been injured had he been wearing a seat belt. CA held that P’s compensation would be reduced by 20% due to P’s having partly “caused” (!) his own injury.
Lord Denning: “is guilty of contributory negligence if he ought reasonably to have foreseen that, if he did not act as a reasonable prudent man, he might be hurt himself”. The question here is not the cause of the accident but the cause of the damage. He says that here the damage was 20% “caused” by the failure to wear a seat belt and “If the plaintiff was to blame in not wearing a seat belt, the damage is in part the result of his own fault”. NB He is not drawing any distinctions between blame, fault and causation. He is right to refrain from doing so, since it leads to massive confusion- see Reeves. The injured party has a duty to lessen or mitigate the damages and therefore, if he fails to do so, he must take some share of the responsibility for the accident.