24 Kristy A. Belton and Jamie Chai Yun Liew citizenship in international and domestic law Citizenship may be understood in many ways. For the purpose of this chapter, it is defined as the legal bond of attachment between a person and a state. It serves as a mobile border, demarcating who is from where and how said person should be treated when outside the borders of her state. In the modern era, it has become an international ordering principle, which rests on the notion of states as self-contained political units that govern defined territories. The emergence of sovereign, independent states that governed their own internal affairs is typically traced to Europe and the Peace of Westphalia, which ended the Thirty Years’ War.1 The peace treaties cemented the demise of the overarching power of the Catholic Church and the Holy Roman Empire and heralded the advent of an international legal system where autonomous states became masters of their own domain and recognized each other’s authority over territory.2 Although many trace the beginning of the present international world order to the Peace of Westphalia, scholars acknowledge that the concepts of statehood and state sovereignty were not simply constructed, endorsed, and applied at this point in time. Instead, the treaties sanctioned or confirmed an interstate system that was already developing, or in existence, out of necessity as a consequence of negotiating peace.3 State sovereignty thus emerged as the dominant organizing principle of the Peace of Westphalia because of the growing recognition that polities were organizing themselves in this way. Furthermore, these peace treaties not only addressed authority over territory but also endorsed authority over individuals, referring to “vassals,” “subjects,” “soldiers,” “inhabitants,” “servants,” “people,” and others.4 Passages referring to such people in the peace treaties were written with the intention to provide protection. That is, state sovereignty included not only the unencumbered right to rule over people but the reciprocal responsibility of protecting them as well. What began as political practice in early Europe solidified in international legal doctrine in the 1930s. The 1930 Convention on Certain Questions Relating to the Conflict of Nationality Law established that it was “in the general interest of the international community to secure that all its members should recognize that every 1 2 3 4 Although this system of international law started in Europe, other polities were folded into this new world order through the expansion of European colonial empires. Polities that were not colonized reluctantly adopted this European model. As a result, by the early twentieth century, the European model of international legal order was universalized. J. H. Currie, Public International Law (2nd ed., Toronto: Irwin Law, 2008). D. Croxton, “The Peace of Westphalia of 1648 and the Origins of Sovereignty” (1999) 21(3) The International History Review 569–591. The Peace of Westphalia comprises a series of treaties signed between May and October 1648 in the cities of Osnabrück and Münster. See, for example, Treaty of Münster (Peace Treaty between the Holy Roman Emperor and the King of France and their respective Allies), October 24, 1648, http://avalon.law.yale.edu/17th_century/westphal.asp. https://doi.org/10.1017/9781108914994 Published online by Cambridge University Press