O. Elias, T. Keywords: Treaties | Legality | Mots clefs: Traités | Légalité | ABSTRACT T.O. Elias starts his course on the problems of the validity of treaties by an introductive study of the grounds of invalidity. He then studies the constitutional limitations to the power of making the treaties as well as a few specific internal restrictions. The author later focuses on the error and fraud and on corruption and coercion. He analyzes the legal procedure of settlement of disputes, and dedicates his last chapter to the consequences of the invalidity of treaties. T.O. Elias commence son co…