Fibrosa Spolka Akcyjna v Fairbairn Lawson Combe Barbour Ltd [1942] UKHL 4 is a leading House of Lords decision on the doctrine of frustration in English contract law.

In July 1939, it entered into a contract with Fairbairn, a British firm, to buy industrial machinery for its plant in Gdynia for £4,800.

The following week, Fibrosa's agents in the UK contacted Fairbairn to request that the initial £1,000 payment be refunded, as "it is now quite evident that the delivery of the machines on order for Poland cannot take place".

As a result, sums paid or rights accrued under the contract before the frustrating event occurs cannot be reclaimed but that all obligations falling due after it are discharged.

The Chief Justice is there using earnest as meaning a prepayment on account of the price, not in the modern sense of an irrevocable payment to bind the bargain, and he is recognizing that the indebitatus assumpsit had by that time been accepted as the appropriate form of action in place of the procedure which had been used in earlier times to enforce these claims such as debt, account or case.

Lord Mansfield C.J., in a familiar passage in Moses v Macferlan, sought to rationalize the action for money had and received, and illustrated it by some typical instances.

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."

"If the defendant be under an obligation from the ties of natural justice, to refund; the law implies a debt and gives this action [sc.

indebitatus assumpsit] founded in the equity of the plaintiff's case, as it were, upon a contract ('quasi ex contractu' as the Roman law expresses it)."

The standard of what is against conscience in this context has become more or less canalized or defined, but in substance the juristic concept remains as Lord Mansfield left it.

This is important because some confusion seems to have arisen though perhaps only in recent times when the true nature of the forms of action have become obscured by want of user.

As Bullen and Leake (Precedents of Pleading, 3rd ed., p. 36) points out, this Act, by s. 3, provided that the plaintiff was no longer required to specify the particular form of action in which he sued, and by s. 49 that (inter alia) the statement of promises in indebitatus counts which there was no need to prove were to be omitted; "the action of indebitatus assumpsit," the authors add, "is [that is by 1868] virtually become obsolete."

He adds: "These fantastic resemblances of contracts invented in order to meet requirements of the law as to forms of action which have now disappeared should not in these days be allowed to affect actual rights."

Yet the ghosts of the forms of action have been allowed at times to intrude in the ways of the living and impede vital functions of the law.

In fact, the common law still employs the action for money had and received as a practical and useful, if not complete or ideally perfect, instrument to prevent unjust enrichment, aided by the various methods of technical equity which are also available, as they were found to be in Sinclair v Brougham.

The claim for repayment is not based on the contract which is dissolved on the frustration but on the fact that the defendant has received the money and has on the events which have supervened no right to keep it.In essence, having decided that the contract was frustrated (as to continue would have been treasonable), the court held that the entire deposit was recoverable by Fibrosa, given the total absence of consideration from the English supplier.

The UK Parliament recognised that this war against the Nazis would give rise to numerous similar claims so, with admirable speed,[2] they enacted the Law Reform (Frustrated Contracts) Act 1943, which provided that: