Civil Liability Act 1961
Extent of liability.
12.—(1) Subject to the provisions of sections 14, 38 and 46, concurrent wrongdoers are each liable for the whole of the damage in respect of which they are concurrent wrongdoers.
(2) Where the acts of two or more persons who are not concurrent wrongdoers cause independent items of damage of the same kind to a third person or to one of their number, the court may apportion liability between such persons in such manner as may be justified by the probabilities of the case, or where the plaintiff is at fault may similarly reduce his damages; and if the proper proportions cannot be determined the damages may be apportioned or divided equally.
(3) Subsection (2) of this section shall apply to two or more persons whose acts taken together constitute a nuisance, even though the act of any one of them taken alone would not constitute a nuisance, not being unreasonable in degree.