Berlia, G. Keywords: Interpretation | Treaties | Mots clefs: Interprétation | Traités | ABSTRACT The question of the interpretation of a legal act raises two main types of problems: the authority competent to interpret and the act to be interpreted. It is precisely the nature of the act to be interpreted, considers G. Berlia, as an essential element of his study. The author successively focuses on the true meaning of the terms "intention of the parties", the so-called clear act rule, the rule of useful effect…