In one sense a contractor always "assumes the risk " of failure to discharge his obligation. For if he commits a breach he will be unable to enforce his contract and will himself be liable in damages. In reality, the risk of failure, in this sense, is imposed upon him by law, rather than assumed by him, for it makes no difference whether or not he is conscious of a doubt as to his ability to perform. But this is not the sort of "assumption of risk" that negatives the element of misreliance and bars a recovery in quasi contract {ante, Sec. 16). To have such a result there must be a conscious "taking of a chance." It must appear that the contractor, when he entered into the contract, actually contemplated a contingency, which, if it happened, would cause him to violate his engagement, and nevertheless contracted without protecting himself against the contingency. In such a case he cannot say, when the contingency happens and he commits a breach, that he relied upon his ability to perform and the consequent enforceability of his contract. He deliberately "took a chance " that his contract might become unenforceable by the happening of that particular contingency, and cannot complain if his venture proved a losing one.

An illustration may serve to make the point clearer. Let it be supposed that A is about to contract for the manufacture of certain machines for B. The delivery of all the machines within four months is a condition of the contract, but the price to be paid by B is a liberal one. A is unaware of any facts that will prevent him from getting the necessary skilled labor to do the work and anticipates no trouble in that direction. But he knows of certain conditions in the steel market that may make it impossible for him promptly to obtain the necessary materials. In view of the attractive terms of the contract, however, he decides to "take a chance" of getting the materials. The contract is duly made, and after part performance by A, he commits a breach. Now, if the breach is due to A's inability promptly to secure his materials - a contingency which he realized might happen - he cannot say that he was mistaken as to his ability to perform and consequently as to the enforceability of his contract. He deliberately took the chance of getting materials, and lost. There is no injustice in denying him relief. Moreover, to allow him to recover the value of his part performance would be to encourage the reckless assumption of contractual obligations. If, on the other hand, the breach is the result of A's inability to obtain competent labor - a contingency wholly unforeseen by him - he may truthfully claim that his party performance was in reliance upon the contract. He did not consciously "take a chance" of getting competent workmen, for he did not realize the possibility of difficulty in that direction. He did not, in the true sense, "assume the risk" of failure from that cause, and consequently, if the other elements of quasi contractual obligation are present, he should be granted relief.

In England, as appears in the chapter dealing with benefits conferred in reliance upon contracts which turn out to be impossible of performance (ante, Sec. 112), the view is taken that the existence in a contract of a condition making the defendant's contractual liability depend upon complete performance by the plaintiff necessarily predicates such an assumption by the plaintiff of the risk of failure, from any cause whatsoever, as to negative misreliance upon the contract. It is accordingly held, as a rule, that one who is prevented by his own breach from enforcing a contract can recover nothing in quasi contract.1 Where the plaintiff's default is due to such impossibility of performance as excuses him from liability for damages, it seems clearly erroneous, as is elsewhere explained (ante, Sec. 112), to raise a presumption that he assumed the risk of the after-event which made performance impossible. Where the plaintiff's default is not legally excusable but constitutes an actionable breach, a presumption that he assumed the risk of the after-event which caused the breach is not so unreasonable. It amounts to a presumption that he realized, when he entered into the contract, that the contingency which eventually brought about his breach might arise. But even in the case of a breach, it would seem fairer to assume, in the absence of evidence to the contrary, that the circumstances leading to the default were unanticipated at the time of the formation of the contract.

It should be added, perhaps, that an express provision in the contract to the effect that the promisor assumes the risk of inability to perform his engagement, and in case of breach shall have no right to recover the value of his part performance, would conclusively show that the promisor deliberately "took a chance" of failure, whether anticipated by him or not. Thus, where the plaintiffs contracted to do some threshing for the defendant and agreed that "if they did not do as good work as any machine in the county could do nothing would be charged," it was properly held that unless the plaintiffs performed according to the terms of their contract they could recover nothing.2