The intervention of public policy aims to protect the aspect of human rights, morality, and the law of the lex fori. With the aim of this, public policy hinders the application of foreign law and serves if necessary to the application of lex fori. The application of public policy should be interpreted strictly. This means the contrast between lex fori and foreign law is not enough to hinder the application of foreign law. However, the sum of the application of foreign law should have contrast with lex fori. Art. 5 of MÖHUK says the public policy rule without any definition. This Article gives importance to the strict interpretation of public policy and says that the foreign law should be clearly contrary to the Türkish public policy. Internal public policy and public policy of private international law are different from each other. Internal public policy means to be contrary to the imperative norms and the sanction is certain invalidity. But in international private law, controversy with the public policy causes the inapplicability of foreign law. Mandatory rules are also interventive norms like public policy. But they are directly applicable to the dispute contrary to public policy. For example exchange rules, customs rules, and the worker protective rules of the labor law.