While trade and exchange rules have existed since antiquity, modern contractual laws have been traceable in the West since the Industrial Revolution (1750), when more and more people were working in factories for cash wages. In particular, the growing strength of the British economy and the adaptability and flexibility of the English common law have led to a rapid evolution of English contract law. The colonies within the British Empire (including the United States and the Dominions) would pass the law of the motherland. During the 20th century, the growth of export trade led countries to adopt international conventions such as the Hague-Visby rules and the Un Convention on International Goods Contracts to promote uniform rules. Contracts are mainly subject to legal and common (judicial) and private law (i.e.dem private contract). Private law first includes the terms of the agreement between the parties exchanging promises. This private right can repeal many of the rules otherwise established by state law. Legal broadcasting laws, such as the Fraud Act, may require certain types of contracts to be executed in writing and with special formalities in order for the contract to be enforceable. Otherwise, the parties can enter into a binding agreement without signing an official written document. For example, the Virginia Supreme Court in Lucy v.
Zehmer, that even an agreement on a piece of towel can be considered a valid contract if the parties were both sane, and showed mutual consent and consideration. Each country recognized by private international law has its own national legal system to govern treaties. While contract law systems may have similarities, they can differ significantly. As a result, many contracts contain a choice of law clause and a jurisdiction clause. These provisions define the laws of the contracting country and the country or other forum in which disputes are settled. Without explicit agreement on such issues in the treaty itself, countries have rules for determining treaty law and jurisdiction over litigation. For example, European Member States apply Article 4 of the Rome I Regulation to decide on the law applicable to the Treaty and the Brussels I regulation on competence.