Niboyet, J.-P. Keywords: Reciprocity | Legal principles | Private international law | Treaties | Mots clefs: Réciprocité | Principes généraux du droit | Droit international privé | Traités | ABSTRACT The theme developed by J.-P. Niboyet in his course is the relations that exist or rather should exist between the general principles of civil law and the treaties which are, after all, just the contracts between the States. After outlining a few general considerations, the author examines the patterns of diplomatic reciprocity, …