As a result of D’s negligence, P’s cancer was diagnosed late and his chances of long term survival were reduced as a result from 42% to 25%. P argued (1) that the reduction in chances of survival WAS injury, or (2) that reduced chances of survival should give rise to liability in its own right. HL rejected “lost opportunity” as giving rise to liability. This case was decided on the traditional guidelines for a tort claim.
Lord Hoffman (majority): The law treats every harmful event as having a single determinate cause. It is therefore impossible to compensate a person for an act which has not caused the harmful event. Here on balance of probabilities the impugned treatment did not ‘cause’ the outcome (it merely reduced P’s survival chances). To allow compensation in proportion to ‘chance’ would contradict this fundamental position that the law takes on causation. Exceptions to the rule, such as loss of a chance where the loss is dependent on third party conduct, is an arguably unprincipled exception. The Fairchild exception (see below) is tightly confined. Another consideration is floodgates, since nearly everything a doctor does affects survival chances by a small percentage.
Minority: Lord Nicholls: floodgates is a bad reason for depriving people of compensation. He also says that since it is a doctor’s duty to protect a patient’s prospects, there ought to be a remedy where this duty is abandoned. Lord Hope says that the enlargement of the tumour itself is physical harm and should be compensated irrespective of effect on survival chances long term.