Nationality is a sensitive issue as it is a manifestation of a country’s sovereignty and identity. Not surprisingly, disputes about citizenship can, and often do, result in tension and conflict, both within and between States. During the 20th century, there was both an increase in the incidence of statelessness around the world and growing awareness of and concern for human rights. International law on nationality thus evolved along two tracks: to protect and assist those individuals who were already stateless, and to try to eliminate, or at least reduce, the incidence of statelessness. Who determines whether or not a person is a citizen of a particular country? In principle, questions of nationality fall within the domestic jurisdiction of each State. However, the applicability of a State’s internal decisions can be limited by the similar actions of other States and by international law. In its Advisory Opinion on the Tunis and Morocco Nationality Decrees of 1923, the Permanent Court of International Justice stated that: “The question whether a certain matter is or is not solely within the domestic jurisdiction of a State is an essentially relative question; it depends on the development of international relations.” In effect, the Permanent Court said that while nationality issues were, in principle, within domestic jurisdiction, States must, nonetheless, honour their obligations to other States as governed by the rules of international law. This approach was reiterated seven years later in the 1930 Hague Convention on Certain Questions Relating to the Conflict of Nationality Laws (1930 Hague Convention). Indeed, many States commented on the Permanent Court’s 1923 Advisory Opinion as it related to the preparation of the 1930 Hague Convention. Most States interpreted the Advisory Opinion as a limitation on the applicability of a State’s nationality‑related decisions outside that State, especially when those decisions conflict with nationality‑related decisions made by other States. The 1930 Hague Convention, held under the auspices of the Assembly of the League of Nations, was the first international attempt to ensure that all persons have a nationality. Article 1 of the Convention states that: “It is for each State to determine under its own law who are its nationals. This law shall be recognized by other States in so far as it is consistent with international conventions, international custom, and the principles of law generally recognized with regard to nationality.” In other words, how a State exercizes its right to determine its citizens should conform to the relevant provisions in international law. Article 15 of the 1948 Universal Declaration of Human Rights (UDHR) declares: “Everyone has the right to a nationality. No one shall be arbitrarily deprived of his nationality nor denied the right to change his nationality.” 8