The article investigates the question of the relationship of dispositive and imperative norms in international commercial law relations based on experience of application of United Nations Convention on Contracts for the International Sale of Goods 1980 (the Vienna Convention). The problems of differentiation of discretionary and mandatory standards are considered as a special perception imperativity in international relations and private discretionary Vienna Convention is proposed to apply a local interpretation of the imperative element in the legislation of Ukraine on foreign economic activity. It is emphasized the need to determine two kinds of imperative norms of international commercial relations: the imperative rules of law, that is applied to a contract by virtue of provisions of conflict of laws, and Super-imperative provisions of the country (countries) law, which is closely connected with the contract, in particular, should be considered by a court or tribunal by virtue of Recognition and Enforcement of Foreign court or arbitral awards.