This chapter is concerned with the issue of the enforceability of promises. How does English law decide whether a promise is to be treated as enforceable by the courts? In investigating this question, the following topics will be considered:

Deeds. These constitute a means of indicating an intention to make an enforceable promise through formal means – that is, putting the promise into a particular type of document.

Consideration. The doctrine of ‘consideration’ is one of the hallmarks of English contract law. It means, in effect, that promises usually do not have to take any particular form, or be put in writing, but will be enforceable if there is mutuality in the agreement – both parties bring something to it. Within this doctrine it will be necessary to consider:

What constitutes ‘consideration’? Does it have to have a monetary value?

What is meant by the requirement that consideration must be ‘sufficient’, though not necessarily ‘adequate’?

Can an action already performed (past consideration) be consideration for a new promise? (Generally, it cannot.)

When will the performance of an existing duty constitute good consideration? The answer will depend on the type of duty.

Promissory estoppel. This doctrine allows a promise unsupported by consideration to be, to some extent, enforced – generally in the context of the variation of an existing contract.

Part payment of debts. Generally, part payment of a debt is not good consideration for the remission of the balance, unless promissory estoppel applies.

Alternative tests of enforceability. Other jurisdictions may use ‘reliance’ as a test of enforceability alongside consideration. To date, English law has made limited use of this test.