By far the most commonly raised and successful defence is that of contributory negligence. It is not a complete defence, although historically it used to be, but it does give the defendant the opportunity to reduce their liability, i.e. they are rendered partially liable. The basis for the defence is to be found in s 1 Law Reform (Contributory Negligence) Act 1945 which provides that if a person suffers damage partly through his own fault and partly through the fault of another, his damages are to be reduced to the extent that the court considers just and equitable. Section 1(1) states:

Where any person suffers damage as the result partly of his own fault and partly of the fault of any other person or persons, a claim in respect of that damage shall not be defeated by reason of the fault of the person suffering the damage, but the damages recoverable in respect thereof shall be reduced to such extent as the court thinks just and equitable having regard to the plaintiff’s share in the responsibility for the damage.