The CISG is a multilateral treaty that governs commercial transactions between signatory countries or contracting states to the CISG. In this webinar, attorney and licensed customs broker Jack Shelton explains the fundamentals of a sales contract including why you need a written contract.Fully elaborated commercial contracts typically identify the governing law and specify the forum that would hear any dispute. This Convention applies to contracts of sale of goods between parties whose places of business are in different States. The CISG is a set of rules that governs the rights of sellers and buyers that engage in contracts involving the international sale of goods. In 1988, the United States and 10 other countries ratified the United Nations Convention on Contracts for the International Sale of Goods (CISG) A choiceoflaw provision in a contract for the sale of goods should be the final word on what law applies, correct? The CISG governs contracts for the purchase and sale of goods between parties located in different contracting states. See our article on Commercial Transactions. Convention on Contracts for the International Sale of Goods (hereinafter, the.