Given that an exit from the EU would not entail any change in the currency of the UK; there should be fewer issues about existing contracts than would be the case if a member of the Eurozone left the EU. However there will still be a number of issues for contracting parties to address.
A key question is whether a particular contract could be terminated as a result of the UK's exit from Europe, particularly as the changed commercial landscape could prompt contracting parties to reassess their current contract arrangements and look for ways to exit those contracts which are no longer required or profitable. Any right of termination would of course depend on the terms of the relevant contract, including any material adverse change and force majeure provisions and any right (express or implied) to terminate on notice. We may see some companies seeking to include a provision in new contracts in the event of a UK exit from the EU. A related issue is interpretation of pre-existing contracts. For example, how would an obligation to comply with a specific piece of EU legislation be interpreted after a UK exit? Similarly, how should a choice of English law as the governing law of a contract be interpreted if, at the time of contracting, EU law formed part of English law but at the time of performance it did not? These are essentially questions of contractual intention. In most cases one supposes that a choice of English law will be interpreted to mean English law as it stands from time to time, subject to any variations, including such variations as may arise from an EU exit. But it is possible that where some key provision of EU law is essential to the operation of a particular contract, so that without it the contract is inoperable or incapable of being performed as originally anticipated, a different result may follow.
There is then the question of new contracts, and whether any EU exit may have an effect on the enthusiasm of parties to choose English law as their governing law. One assumes that is unlikely to be the case in many instances, given that English domestic commercial law has its own well-developed and respected rules, which have largely been unaffected by EU intervention. That is certainly the case in the core area of contract law. In some other areas, however, one can see that the position may be different. For example, the ability of the EU to legislate on a supra-national level in respect of matters such as the holding of securities in dematerialized form, may encourage the listing and trading of such securities in the remaining EU jurisdictions, under arrangements incorporating relevant EU law, rather than the listing and trading of such securities in England under essentially English law arrangements.
Finally in the contract area, the validity and effectiveness of any contractual choice of law is very unlikely to be affected by an EU exit. In other words, a choice of English law (or Scots law, or any other law) in a contract will continue to be effective, whether in England, Scotland or in the remaining EU Member States. This would follow from the continued operation within the EU of the Rome I Regulation, governing choice of law in contracts, which in effect enforces any choice of law made by contracting parties, whatever law they have chosen. Although the Regulation would cease to have effect in the United Kingdom, the pre-Regulation rules are to very similar effect and would give rise to the same result i.e. any expressly chosen governing law will generally be enforced.
Outside the contract area, commercial disputes sometimes involve allegations of liability arising in tort or delict, or claims for unjust enrichment and the like. Such disputes can give rise to considerable uncertainty and risk in international cases, because it may be difficult to predict which law to apply. EU legislation (the Rome II Regulation) presently allows commercial parties to select in advance, by contract, the law to govern not only their contractual but also their non-contractual rights and liabilities. That was not the position under the English common law, however. One would hope that any replacement provisions on choice of law in tort following an EU exit would mirror the present EU provisions, but again there is scope for disagreement and uncertainty about this, which may have an effect on the desirability of England as a forum for the resolution of some commercial disputes.