A contract may also be discharged, before breach, by implied waiver, that is, by the parties entering into a new contract inconsistent with the performance of the old; as if A. contract to sell Blackacre to B. for 1,000l., and it be agreed between them, before breach, that C. shall be the purchaser instead of B. (p); or that B. shall take Whiteacre instead. But in order that a new agreement may operate as an implied waiver of a preexisting contract, its terms must be inconsistent with the performance of the earlier contract; it must be such as can only be carried out by the entire abandonment of the old agreement. A mere alteration of some term or terms of the old contract is not sufficient (q).

2. Implied waiver.

Co., 2 Ex. 519, 5 Ex. 696; Major of Berwick v. Oswald, 1 E. & B. 295; Spence v. Healey, 8 Ex. G68.

(m) Nash v. Armstrong, 10 C. B. N. S. 259.

(n) Lanesborough v. Ockshott, 1 Bro. P. C. 151; Hill v. Gomme, 1 Beav. 540; Webb v. Hewitt, 3 K. & J. 438.

(o) Steeds v. Steeds, 22 Q. B. D. 537.

(p) Moore v. Marrable, L. R. 1 Ch. 217, 222.

(q) Price v. Dyer, 17 Ves. 356; Robinson v. Page, 3 Russ. 114;

Besides this, the new agreement must be perfectly valid, and enforceable at law (r), or at least, in equity. For example, if A. sell Blackacre to B. for 1,000l., the sale to be completed at one month's date, and before breach it be agreed in writing, duly signed, that the price shall be 950l., or that two-thirds of the purchase money shall be left on mortgage, or that an inferior title to that stipulated for shall be shown, or that the time for completion shall be extended to six weeks, the other obligations under the contract are not discharged (s), although it is true that from one point of view they may be regarded as incorporated in an entirely new agreement (t). And if, after such a contract, but before breach, the parties orally agree that C. shall be the purchaser instead of B., or that Whiteacre shall be substituted for Blackacre, it appears that the original contract still remains undischarged, and may be specifically enforced on either side. For, as we have seen (u), the law requires all contracts for the sale of land to be put in writing and signed by the party to he charged, or else they shall not be enforced. Parol evidence is therefore inadmissible to prove the new agreement for what it purports to be, that is, a new contract inconsistent with the performance of the old. And it has been decided that in such case the new agreement shall not be put in evidence, without signed writing, to establish an implied parol waiver of the old contract (x). If, however, the new agreement were specifically enforceable in equity under the doctrine of part performance (y), it is thought that, according to the present law and practice, it would effectively operate as a discharge of the old contract, and might, for that purpose, be proved by oral evidence (z). And if it were an express term of the new agreement that the old contract should be abandoned, it appears that such express waiver (a) might be proved by parol evidence, although the other terms could not (b). So also if, after making the contract but before breach, the parties agree by word of mouth to alter some term or terms only of the contract, the obligation of the contract is not in any way discharged, and either party may enforce specific performance of the contract in its original form (c). For all the terms of an agreement for the sale of land must be put into writing and signed in order to satisfy the Statute of Frauds (d); so any alterations in such terms must necessarily assume the same form (e). And the doctrine of setting up a parol variation in defence to an action for specific performance (f) applies only where the term orally agreed upon is assented to at the time of, and not after, the formation of the written contract (g). But where a parol agreement made after the execution and varying the terms of a written contract to sell land has been so acted upon that it would be fraudulent or unfair to insist on the original contract, the variation may be asserted as a defence to an action for specific performance of the contract contained in the memorandum (h). And the contract, as so varied, may be decreed to be specifically enforced, if the acts of part performance have been sufficient to satisfy the equitable doctrine in that behalf (i).

A contract, invalid for want of writing, cannot be set up as an implied waiver of a prior contract.

Vezey v. Rashleigh, 1904, 1 Ch. 634; see also Goss v. Nugent, 5 B. & Ad. 58; Harvey v. Grabham, 5 A. & E. 61; Stowell v. Robinson, 3 Bing. N. C. 928.

(r) Stead v. Dawber, 10 A. & E. 57; Marshall v. Lynn, 6M.&W. 109; Moore v. Campbell, 10 Ex. 323; Noble v. Ward, L. R. 2 Ex. 135. These are cases relating to the 17th section of the Statute of Frauds: but their principle is equally applicable to cases governed by the 4th; see preceding note; Marshall v. Lynn, 6 M. & W. 109, 117. The statements in Fry, Sp. Perf. Sec. 1039, p. 475, 3rd ed., 448, 4th ed., appear to have been made in ignorance of these decisions.

(s) See note (q), above.

(t) See note (r), above.

(u) Above, p. 3.

{x) See note (r), above.

Parol alteration of the terms of a contract required to be in writing.

The alterations must be put in writing and signed.

Parol variation may be effectual where there is part performance.

(y) Above, p. 11.

(z) See above, p. 910 and n. (o).

(a) Above, pp. 908 - 910.

(b) See Noble v. Ward, L. R. 1 Ex. 117, 2 Ex. 135, as to the contract of Aug. 12.

(c) See above, p. 910 and n. [q).

(d) Above, pp. 3, 4.

(e) See cases cited in n. (r) to p. 911, above; Robson v. Collins, 7 Ves. 130, 133.

(/) Above, p. 705.

(g) See cases cited above, n. (7) to p. 910; Fry, Sp. Perf. Sec. 809, p. 372, 3rd ed., 350, 4th ed.

(h) Legal v. Miller, 2 Ves. sen. 299; Price v. Dyer, 17 Ves. 353, 361.