English Law/Contract/Certainty

While agreement is the basis for all contracts, not all agreements are enforceable. A preliminary question is whether the contract is reasonably certain in its essential terms, or , such as price, subject matter and the identity of the parties. Generally the courts endeavour to "make the agreement work", so in , the House of Lords held that an option to buy softwood of "fair specification" was sufficiently certain to be enforced, when read in the context of previous agreements between the parties. However the courts do not wish to "make contracts for people", and so in , a clause stipulating the price of buying a new van as "on hire purchase terms" for two years was held unenforceable because there was no objective standard by which the court could know what price was intended or what a reasonable price might be. Similarly, in  the Court of Appeal held that because the price and quantity to buy would be uncertain, in part, no term could be implied for to give reasonable notice before terminating its purchasing agreement. Controversially, the House of Lords extended this idea by holding an agreement to negotiate towards a future contract in is insufficiently certain to be enforceable.

While many agreements can be certain, it is by no means certain that in the case of social and domestic affairs people want their agreements to be legally binding. In  held that Mr Balfour's agreement to pay his wife £30 a month while he worked in  should be presumed unenforceable, because people do not generally intend such promises in the social sphere to create legal consequences. Similarly, an agreement between friends at a pub, or a daughter and her mother will fall into this sphere, but not a couple who are on the verge of separation, and not friends engaged in big transactions, particularly where one side relies heavily to their detriment on the assurances of the other. This presumption of unenforceability can always be rebutted by express agreement otherwise, for instance by writing the deal down. By contrast, agreements made among businesses are almost conclusively presumed to be enforceable. But again, express words, such as "This arrangement... shall not be subject to legal jurisdiction in the law courts" will be respected. In one situation, statute presumes that between a trade union and an employer are not intended to create legal relations, ostensibly to keep excessive litigation away from.

In a limited number of cases, an agreement will be unenforceable unless it meets a certain form prescribed by statute. While contracts can be generally made without formality, some transactions are thought to require form either because it makes a person think carefully before they bind themselves to an agreement, or merely that it serves as clear evidence. This goes typically for large engagements, including the sale of land, a lease of property over three years, a consumer credit agreement, and a. A contract for guarantee must also, at some stage, be evidenced in writing. Finally, English law takes the approach that a gratuitous promise, as a matter of contract law, is not legally binding. While a gift that is delivered will transfer property irrevocably, and while someone may always bind themselves to a promise without anything in return to deliver a thing in future if they sign a that is witnessed, a simple promise to do something in future can be revoked. This result is reached, with some complexity, through a peculiarity of English law called the doctrine of consideration.