2.2 Causes of statelessness Statelessness occurs for a variety of reasons which can be grouped into three categories: a) causes linked to dissolution and separation of States and transfer of territory between States; b) causes linked to the complex, technical operation of citizenship laws or administrative practices; and c) causes linked to discrimination or arbitrary deprivation of nationality.27 Causes linked to dissolution and separation of States and transfer of territory between States Firstly, statelessness often arises in the context of State dissolution: the turbulent dissolution of the Soviet Union and the Yugoslav Federation caused internal and external migration that left millions stateless throughout Eastern Europe and Central Asia. Twenty years later, hundreds of thousands of people in the region remain stateless or at risk of statelessness. The post-colonial formation of States has been another major cause of statelessness. Large populations have remained without citizenship as a result of decades of such state-building processes in Africa and Asia, which involved defining who are citizens of the independent State. Technical causes Secondly, people may become stateless as a result of the complex, technical operation of citizenship laws or administrative practices. States have the right to determine whom they consider to be a citizen and have adopted a wide range of approaches in this field. Within this complex international maze of citizenship laws, many people find that they fall through the cracks between them. An individual can, for example, become the victim of a conflict of laws, in which two States each claim that the other is responsible for the bestowal of nationality. This is especially likely to happen when a person’s State of birth grants nationality by descent (jus sanguinis), while his or her parents were born in a State that attributes nationality by birth on its territory (jus soli). In addition, some States employ a mechanism whereby automatic loss of nationality occurs, for instance after a prolonged absence from the country (in some States as few as three or five years is considered a “prolonged absence”).28 Failure or inability to undertake what might be considered a simple administrative endeavour can also lead to statelessness. Lack of registration of children at birth – a pervasive problem in many developing countries – leaves many children without proof of where they were born, who their parents were or where their parents were from. Not having a birth certificate does not automatically indicate the lack of citizenship, but in many countries, and in today’s increasingly mobile world of migrants, not having proof of birth, origins or legal identity increases the risk of statelessness. Discrimination and arbitrary deprivation of nationality Thirdly, underlying causes in most situations of statelessness are discrimination and arbitrary deprivation of nationality. Ethnic and racial discrimination as well as discrimination affecting women and children are particularly topical. 27 UNHCR, Nationality and Statelessness: A Handbook for parliamentarians, 2005, pp. 27-39. 28 Ibid. p. 33. in the United Kingdom 23