A clearly recognisable trend of the past decades in the field of international commercial law and, in particular, in international commercial arbitration, is to avoid too precise references to the legal mechanisms for identifying which country's law governs an international legal relationship – legal mechanisms that usually go under the names of conflict of laws, private international law or choice of law. This article intends to show that private international law is not an anachronistic or redundant heritage of old fashioned, national sovereignty-obsessed lawyers without an understanding for international business transactions. The analysis will show that rules of choice of law contained in national laws are relevant to international arbitration, that disappearance from arbitration rules of reference to private international law may create unpredictable results and is not necessarily the optimal solution for business transactions. The relevance of private international law to international arbitration will be shown by identifying some of the main contract terms that, among those often used in various commercial contracts, run the risk of being governed by a law different from the law chosen by the parties. To this aim, the bases for restricting party autonomy need to be recognised, and this assumes an exercise of private international law. This will permit us to indicate not only which areas of the contract might be subject to a law different from the law chosen by the parties, but also which country's law may be applicable instead of the law that the parties had chosen. Finally, to verify whether these restrictions to party autonomy are relevant even though the contract contains an arbitration clause, the article will succinctly analyse the criteria that may make them applicable not only to a court of law, but even to international arbitration.