University of Pennsylvania Journal of International Law
Since the Treaty of Westphalia in 1648, international law has basically been understood as law governing the relations among sovereign nation states. With minor exceptions, such as regimes governing maritime commerce (the law merchant) and agreements regarding the treatment of religious minorities (like the mutual commitments of tolerance among Christian states in the Treaty of Westphalia itself), nation states were the major subjects of international law. States were autonomous, independent, and equal. States were governed by laws to which they all consented, in the form of bilateral or multilateral treaties and customary practices to which they acceded over time. Positivists, such as Emmerich de Vattell, argued that states were bound only by such laws. Enlightenment philosophers, such as Jean-Jacques Rousseau, argued that natural law principles should also be binding on states. Despite differing views on the legitimate sources of international law, it was generally accepted that it governed states alone.
International Law from the Bottom Up: Fragmentation and Transformation, 34 U. Pa. J. Int'l L. 687
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