Lauterpacht, H. Keywords: Treaties | Preparatory work | Interpretation | Mots clefs: Traités | Travaux préparatoires | Interprétation | ABSTRACT H. Lauterpacht, in the introduction of his course, writes that the study of the cases of interpretation of treaties by the international and national courts enable proving the utility of the various rules of interpretation, elaborated with care, which we encounter in the treaties of international law; it leads us to conclude on their less practical significance, he notes. …