Certainty in English law sets out rules for how judges will interpret, sever or put contracts, trusts and other voluntary obligations into effect.
[2] Courts may also look to external standards, which are either mentioned explicitly in the contract[3] or implied by common practice in a certain field.
A preliminary question is whether the contract is reasonably certain in its essential terms,[5] such as price, subject matter and the identity of the parties.
[8] Similarly, in Baird Textile Holdings Ltd v M&S plc[9] the Court of Appeal held that because the price and quantity to buy would be uncertain, in part, no term could be implied for M&S 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 good faith is insufficiently certain to be enforceable.