calculation of compensatory damages. It requires the breaching
party to pay as damages an amount that will provide the non-breaching party with the financial equivalent of performance:
John D. McCamus, The Law of Contracts, 2nd ed. (Toronto:
Irwin Law Inc., 2012), at p. 871; and Angela Swan and Jakub
Adamski, Canadian Contract Law, 3rd ed. (Markham, Ont.:
LexisNexis, 2012), at pp. 381-83.
 The common law places several limits on the expectancy
principle: see McCamus, at pp. 877-82; and Swan and Adamski,
at p. 471. One limit is the minimum performance principle. The
principle has been expressed in several different ways. In Open
Window Bakery, at paras. 11 and 20, the Supreme Court of Canada expressed the principle this way: in cases where the defaulting party had alternative modes of performing the contract,
damages are calculated on the basis of the mode of performance
least burdensome to the defaulting party and least profitable to
the non-breaching party.
 The jurisprudence and legal literature contain other for-
mulations of the minimum performance principle:
( i) “damages for breach of a contract with alternative perfor-
mances are assessed by reference to the promisor’s mini-
mum or least extensive performance”: Michael G. Pratt,
“Damages for Breach of Contracts with Alternative Perfor-
mances” in Jeff Berryman and Rick Bigwood, eds., The Law
of Remedies: New Directions in the Common Law (Toronto:
Irwin Law, 2010), p. 105, at p. 107;
( ii) “where the option of fulfilling one of two alternative promises rests with the promisor who is in default, the measure of
damages is the loss caused by reason of the promisor failing
to perform the promise with the lesser value”: Stewart v.
Cran-Vela Rental Co., Inc., 510 F.2d 982 (U.S. C.A. 5th Cir.
1975), at p. 986; and
( iii) damages are assessed “on the basis that the defendant will
perform the contract in the way most beneficial to himself
and not in the way that is most beneficial to the plaintiff”:
Withers v. General Theatre Corp.,  2 K.B. 536 (C.A.),
at p. 549.
 In Withers, at p. 549, the English Court of Appeal gave a
simple example of the principle in operation. If a vendor agreed
to sell a purchaser 800 to 1,200 tonnes of a certain commodity
but failed to deliver any amount, the court would assess
damages on the basis the vendor had failed to supply the lower