[3] However, the Court rejected this defence as beyond its jurisdiction, refused to receive evidence of it and gave judgment against Moses; holding that his endorsement establishing his liability.

Lord Mansfield gave a number of settled instances where the action lay, but the instant case did not fall within any of them.

Lord Mansfield then held,"This kind of equitable action, to recover back money, which ought not in justice to be kept, is very beneficial, and therefore much encouraged.

It lies for money which, ex aequo et bono, the defendant ought to refund; it does not lie for money paid by the plaintiff, which is claimed of him as payable in point of honour and honesty, although it could not have been recovered from him by any course of law; as in payment of a debt barred by the Statute of Limitations, or contracted during his infancy, or to the extent of principal and legal interest upon an usurious contract, or, for money fairly lost at play: because in all these cases, the defendant may retain it with a safe conscience, though by positive law he was barred from recovering.

In one word, the gist of this kind of action is, that the defendant, upon the circumstances of the case, is obliged by the ties of natural justice and equity, to refund the money.

"[7]Lord Mansfield's judgment in Moses v Macferlan is credited with founding the entire common law of unjust enrichment.

"[9] Birks observes that Mansfield's classification of unjust factors, "was endowed with the authority of scripture and broadcast to the world by Blackstone.