Nation and community are important imaginations through which human beings try to understand and organise themselves (Black, 1993; Wang, 1992). It is commonly believed that the concept of nationality is related to “nation” while the concept of citizenship is connected to “state” (Gans, 2017: 108-109; Mubah and Anabarja, 2011: 66), and nationality is a more cultural identity while citizenship is conceptualised more as a “rights and duties” concept or political identity (Jamieson, 2002: 516; Mubah and Anabarja, 2011: 66). In international law and international politics, nations and states are commonly conceived of as a single entity — “nation-states” — as the international system is composed of nation-states and the distinction between cultural and political identity is vague and not necessarily useful on most occasions. For example, nationality was defined in the 1929 Harvard Research in International Law as “the status of a natural person who is attached to a state by the tie of allegiance”, where “state” rather than “nation” was used to define “nationality” (Harvard Law School, 1929). This paper treats nationality and citizenship as interchangeable unless specified otherwise.
Dual nationality had long been unpopular for States. For example, States commonly raise the issue of “embarrassment in diplomatic relations” and “the threat of divided allegiance in wartime” to disallow dual nationality (Guo, 2018: 131; Irving, 2013). The international community has adopted treaties to reduce dual nationality and deal with associated issues such as military obligations…