One of the parties to the contract may so act that he makes it actually impossible for the adversary party to perform, or so that he delays performance on the part of the adversary party before the time fixed by the terms of the contract for performance. In some cases, impossibility in this sense is not impossibility of the technical kind which would have operated as a discharge of the contract if such impossibility had not been caused by one of the parties thereto,1 but it consists of some act or omission which makes performance more difficult, dangerous, or expensive, although it remains possible in the technical sense of the term.2 In other cases the act of the party to the contract causes impossibility of such a sort that it would have amounted to a technical impossibility which would have discharged the adversary party if it had not been due to the fault of one of the parties to the contract.3 In either case it must be considered apart from technical impossibility, since on the one hand it discharges the adversary party whether it amounts to such technical impossibility or not;4 and, on the other hand, the party who has caused such impossibility in this sense is not himself discharged from liability, but remains liable either for compensation under the contract or for damages, as the case may be,5 since the party who has caused such impossibility in this sense has broken the contract.

The term "renunciation" is ordinarily used where the party who renounces the contract intends to do so and notifies the adversary party of such intention, either by his words or by his conduct. In prevention of performance, the party who prevents performance does not always intend his conduct to have this result,6 and he frequently does not give the adversary party an opportunity of knowing that performance has been prevented, until the adversary party has commenced performance or, in some cases, until he has performed the greater part of the covenants into which he has entered. The act of the party who has prevented the adversary party from performing is analogous to renunciation on his part;7 and many of the cases of prevention of performance could be explained as well on the theory of renunciation as on the theory that one of the parties has voluntarily prevented the other from performing. It differs from renunciation, however, since, in many cases, the party who is prevented from performing does not know of the existence of the facts which prevent him from performing in time to alter his position so as to mitigate damages.8 The two forms of breach are, however, much alike, and in many cases practically, identical.

1 See Sec. 2667 et seq.

2 See Sec. 2705 et seq. 3 See Sec. 2667 et seq. 4 See Sec. 2924.

5 See Sec. 2922 and 2923. 6 See Sec. 2919 et seq.

7 See Sec. 2882 et seq.

The nature of breach of this sort is so closely connected with the consequences that arise therefrom, that many of the general principles of breach of this sort can best be discussed in connection with such consequences.9