N. Van Kleffens, E. Keywords: Sovereignty | Mots clefs: Souveraineté | ABSTRACT After an introduction to a study of the etymology of the word "sovereignty," E.N. Van Kleffens focuses on sovereignty as it is understood in the Antiquity and Middle Ages. He focuses on the modern era and the status of sovereign States in the international Community under natural law and then according to more modern theories. He examines some special issues (legal characteristics of sovereignty, the relationship of sovereignty …