This paper is aimed to highlight some aspects of legal comparison undertaken by the Judiciary, namely, the practice of using foreign Law in order to resolve legal disputes. With this regard, a distinction should be pointed out between normative use of foreign law, and dialectical use, addressed to the interpretation of national law. On one hand, the normative use of foreign law is connected with the sources of national legal system and also, with the feasibility that it becomes part of the domestic law. The European system of protection of fundamental rights, involving the European Court of Human Rights, the European Union, and the States thereof, is an example of the aforementioned use of foreign law. On the other hand, by means of the dialectical use of foreign law, judges base their decisions on a critic comparison with the latter. Therefore, the outcome are new and different arguments for the judgement. Finally, at a global level, the «communication» between Courts allows the unification of the global order through the legal comparison.