Legal certainty can influence the life of a bargain at a three crucial phases. These can be divided into pre-contractual, contractual and post-contractual. The logic behind this division in relation to legal certainty could partly be explained by understanding the emphasis that English contract law places on individual ethics, on the one hand and sanctity of agreements on the other. Thus the emphasis on bargaining [Atiyah] rather than on exchange of promises imposes a reading of the concept of legal certainty in that light. As a result pre-contractual negotiation may have little influence if any on the bargain, to some degree this fortified legal certainty rather than compromises it. on the other hand English doctrine of contract law would not concede except in exceptional circumstances to any variation to the bargain [unless freely undertaken, or agreed upon in the contract], nor a walk away from the bargain. The English court will not write a bargain for the parties, nor tolerate parties walking away from the bargain. There is a minimal role to substantive fairness or cooperative ethics in this phase. There is absoluteness to the bargain Parties are expected to comply with those obligation freely undertaken in the contract. Thus the contractual phase is also characterised by a great degree of certainty, possibly greater than the pre-contractual phase. Finally the pre-contractual phase, where one may argue that legal certainty will depend on the conduct and behaviour of the parties. On the one hand parties are expected to uphold a certain standard, for example mitigate a loss, or would be substituted by the reasonable man, taking into account principles common to open and fair dealing, and the principle of proportionality, which would affect the expected bargain [limits to the expectation interest- See Ruxely electronics]

Theory of English Contract law that shapes legal certainty

The ethos of English contract law can be best described as ‘essentially individualistic’ (Brownsword). The corner stone of that nature of English contract law are none other than the principles of freedom of contract, and the sanctity of agreements. This notion has survived despite the resurrection of welfarism ethics into English Contract law, and insofar as parties enter into binding agreements, under a 19th-century paradigm conforming to a carefully delineated doctrinal application, i.e. offer, acceptance, consideration, etc… The parties must agree on all the essential terms of the contract in order to have a binding agreement.