Z. Ehler, Sidney Keywords: Roman Catholic Church | Treaties | Pope | Mots clefs: Eglise | Traités | Pape | ABSTRACT According to Sidney Z. Ehler, a concordat is an international agreement between the Pope and a State relating to the legal situation of the Catholic Church of that state. The author begins his study with a presentation of the two parties to the concordat: the Pope and the State. He next examines the characteristics of the concordat as an international agreement, later examines the characteristics of th…