The classic deﬁ nition of consideration was given in Currie v Misa 1 by Lush J, who said:
A valuable consideration, in the sense of the law, may consist either in some right, interest proﬁ t or beneﬁ t accruing to the one party [the promisor], or some forebearance, detriment, loss or responsibility given, suffered or undertaken by the other [the promisee]. In short, consideration is either a beneﬁ t to the promisor or a detriment to the promisee or, in Pollock’s words, ‘the price for which the promise of the other is bought, and the promise thus given for value is enforceable’. 2
Consideration is necessary for all contracts, except contracts made by deed under seal. The essence of the requirement is that gratuitous promises cannot be enforced. Thus, for example, if D promises to give $1,000 to C but subsequently changes his mind, C has no cause of action against D for breach of contract, since C gave no consideration for D’s promise; but if D’s promise to pay the $1,000 had been given in return for C’s promise to look after D’s pets while D was away on holiday, then C could succeed against D.