Ehrlich, Ludwik Keywords: Law of treaties | Interpretation | Mots clefs: Droit des traités | Interprétation | ABSTRACT After some methodological observations, Ludwik Ehrlich begins his course with a history of the issue. He presents some basic questions related to terminology, the legal nature of interpretation, and the rules for the interpretation of treaties. He then studies the essential assumptions of interpretation, and then addresses the issue of the search for willingness in the text and the issue of the search for the willingness outside the text. Après quelques observatio…