Each country recognized by land law has its own national legal system to regulate contracts. While contract law systems may have similarities, they may have significant differences. As a result, many contracts contain a choice of law clause and a jurisdiction clause. These provisions govern the laws of the country governing the contract and the country or other forum in which disputes are resolved. Unless an express agreement on such matters is reached in the contract itself, countries will have rules to determine the law applicable to the contract and the jurisdiction for disputes. For example, European Member States apply Article 4 of the Rome I Regulation to decide on the law governing the Treaty and the Brussels I Regulation to decide on jurisdiction. While such agreements can be commercially attractive, the question of whether or not they are legally enforceable is very different. This is a question that usually arises when one party decides not to pursue the next phase of the undertaking and the other claims to have suffered loss or damage as a result of that decision. Although the European Union is fundamentally an economic community with a set of trade rules, there is no such thing as a comprehensive “EU contract law”. In 1993, Harvey McGregor, a British lawyer and academic, drafted a “Code of Contracts” under the auspices of the English and Scottish Law Commissions, which was a proposal to unify and codify the treaty laws of England and Scotland.
This document was proposed as a possible “Treaty Code for Europe”, but tensions between English and German jurists have led to the fact that this proposal has so far been cancelled.  Some treaties are subject to multilateral instruments that require an unelected court to dismiss cases and require recognition of the decisions of the competent courts on the basis of a jurisdiction clause. For example, the instruments of the Brussels regime (31 European States) and the Hague Jurisdiction Agreement (European Union, Mexico, Montenegro, Singapore), as well as several legal acts relating to a specific area of law, may require courts to enforce and recognize choice of law clauses and foreign judgments. If the terms of the contract are uncertain or incomplete, the parties may not have reached an agreement in the eyes of the law.  An agreement does not constitute a contract, and failure to agree on key issues that may include elements such as price or safety may result in the failure of the entire contract. However, a court will attempt to make commercial contracts possible by interpreting an appropriate interpretation of the contract.  In New South Wales, even if a contract is uncertain or incomplete, the contract may bind the parties if there is a sufficiently secure and comprehensive clause requiring the parties to submit to arbitration, negotiation or mediation.  Another dimension of the theoretical debate on contracts is their place and relationship to a broader law of obligations […].