This book endeavours to provide a brief presentation of the instances when Romanian courts are entitled to apply to a certain contract a law that is different than the one chosen by the parties thereto to govern it. All these instances are limits to the principle of party autonomy in Private International Law. These limits usually represent either the cultural or historical heritage of the legal system of the respective court or the effort of the legislator to protect its own citizens. Under Romanian private international law, the limits to the principle of party autonomy that represent the subject matter of this study are the following: public policy, overriding mandatory provisions, fraud, the impossibility to determine the content of a foreign law, the inexistence of a foreign element and the requirement that the rules chosen by the parties are laws, not rules of law.