(A) THE PRINCIPLE OF NECESSITY
In the same way that there are general principles of compulsion and exploitation on which a number of specific grounds of restitution are based, there is also a general principle of necessity by reference to which a number of specific grounds of restitution can be identified. Although the existence of a general principle of necessity is beyond doubt in English law, the principle is not well developed in Common Law legal systems, unlike civil law systems which have a well developed doctrine of negotiorum gestio which is applicable where the claimant has provided a benefit to the defendant in circumstances of necessity. Consequently, in English law the ambit and rationale of necessity within the law of restitution is a matter of some uncertainty. But it is clear that restitution by reference to necessity exists. This has been recognized by the Supreme Court in The Kos, where, whilst a general rule against restitution on the ground of necessity was acknowledged, the exceptions to it were considered to be more important.
-  It was recognized by the House of Lords in Re F (Mental Patient:Sterilisation)  2 AC 1.
-  See JP Dawson, ‘Negotiorum Gestio: The Altruistic Intermeddler’ (1961) 74 Harv LR 817; J Kortmann,Altruism in Private Law: Liability for Nonfeasance and Negotiorum Gestio (Oxford: Oxford University Press,2005).
-  ENE Kos 1 Ltd v Petroleo Brasileiro SA (No 2)  UKSC 17,  2 AC 164,  (Lord Sumption).
-  Citing Falcke v Scottish Imperial Insurance Co (1886) 34 Ch D 234, 248 (Bowen LJ).