(C) THE RATIONALE OF THE NECESSITY PRINCIPLE
Even where a claimant who has transferred a benefit to the defendant can be considered not to have been acting voluntarily for him or herself, it is still important to determine whether the claimant was indeed acting in circumstances of necessity, which requires careful consideration as to why grounds of restitution founded on necessity should be recognized. Two possible justifications can be identified.
(i) Public Policy
The first justification for recognizing grounds of restitution founded on necessity is for reasons of public policy to encourage the claimant to intervene to assist others who are in need of help. This seems to be the reason why a doctrine of maritime salvage exists, as Eyre CJ accepted in Nicholson v Chapman14 when he said that: ‘Principles of public policy dictate to civilised and commercial countries, not only the propriety, but even the absolute necessity, of establishing a liberal recompense for the encouragement of those who engage in so dangerous a service.’
But the doctrine of maritime salvage has usually been treated as sui generis and probably has little if anything to do with the law of restitution at all.15 More generally, whilst public policy can be used to explain why grounds of restitution founded on necessity ought to be recognized, the notion of public policy is not sufficiently certain to predict when the claimant was acting in circumstances of necessity. Reliance on public policy by itself lays the law of restitution open to the charge of palm-tree justice.