United Nations Convention on Contracts for the International Sale of Goods

The United Nations Convention on Contracts for the International Sale of Goods (CISG; the Vienna Convention) is a treaty that is a uniform international sales law. As of the end of 2015, it has been ratified by 84 states that account for a significant proportion of world trade, making it one of the most successful international uniform laws. Vietnam was the most recent state to ratify the Convention, having acceded to it on 18 December 2015.

The CISG was developed by the United Nations Commission on International Trade Law (UNCITRAL), and was signed in Vienna in 1980. The CISG is sometimes referred to as the Vienna Convention (but is not to be confused with other treaties signed in Vienna). It came into force as a multilateral treaty on 1 January 1988, after being ratified by 11 countries.

The CISG allows exporters to avoid choice of law issues, as the CISG offers "accepted substantive rules on which contracting parties, courts, and arbitrators may rely". Unless excluded by the express terms of a contract, the CISG is deemed to be incorporated into (and supplant) any otherwise applicable domestic law(s) with respect to a transaction in goods between parties from different Contracting States.