The diversity of languages and legal systems can enrich the possibilities of understanding and developing international law, but it can also represent an instability and unsafety factor to the international scenario. This multilegal-system and multilingual scenario adds to the complexity of international law and poses new challenges. One of them is legal translation, which is a field of knowledge and professional skill that has not been the subject of theoretical thinking on the part of legal scholars. How to negotiate, draft or interpret an international treaty that mirrors what the parties, – who belong to different legal cultures and who, on many occasions, speak different mother tongues – ,want or wanted to say?