304 Agata Szwed, Statelessness in the Context of the Migration Crisis in Europe: A Growing... In practice, the status of statelessness developed by the above-mentioned conventions has proven to be insufficient, which is why the literature3 divides de iure stateless persons − persons who formally do not have the citizenship of any country because they have lost or have never acquired it (in accordance with Article 1 CRSSP), and de facto stateless persons − persons who formally have national citizenship but cannot effectively exercise their rights (they are without legal residence, but cannot be deported or they lack access to some basic rights).4 As can be seen, the concept of statelessness is strictly defi ned in opposition to the concept of citizenship. Although it has not been defi ned expressis verbis in international documents, the general understanding of it, formulated in the case of the International Court of Justice in the Nottebohm case, has gained general acceptance: According to the practice of States, to arbitral and judicial decisions and to the opinion of writers, nationality is a legal bond having as its basis a social fact of attachment, a genuine connection of existence, interest and sentiments, together with the existence of reciprocal rights and duties.5 The right to citizenship is ensured in Article 15 of the 1948 Universal Declaration of Human Rights (‘everyone has the right to a nationality’), as well as in regional acts of human rights protection.6 The international community recognises two main ways of acquiring citizenship: ius soli (law of the land − the acquisition of citizenship by the mere fact of being born on the territory of a given country) or ius sanguinis (law of the blood − inheritance of citizenship from parents). Statelessness occurs when a person falls between the cracks in the operation of these different laws, failing to obtain any nationality or losing his or her only nationa- 1989 Convention on the Rights of the Child (arts 7 and 8); the 1990 International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families (art 29); the 2006 Convention on the Rights of Persons with Disabilities (art 18); the 1997 European Convention on Nationality; the 2006 Council of Europe Convention on the Avoidance of Statelessness in relation to State Succession. 3 See United Nations High Commissioner for Refugees (UNHCR), Guidelines on Statelessness No 1: The Definition of ‘Stateless Person’ in Article 1(1) of the 1954 Convention relating to the Status of Stateless Persons, 20 February 2012, HCR/GS/12/01. 4 See Katja Swider and Maarten Den Heijer, ‘Why Union Law Can and Should Protect Stateless Persons’ (2017) 19 European Journal of Migration and Law 108 and the literature cited there. 5 6 ICJ 1955/25 Nottebohm case (Liechtenstein v Guatemala) [ICJ 1955]. This right is provided in regional human rights acts: the 1948 American Declaration of the Rights and Duties of Man (art 19); the 1969 American Convention on Human Rights (art 20); the 1990 African Charter on the Rights and Welfare of the Child (art 6); the 2004 Arab Charter on Human Rights (art 29); the 2005 Covenant on the Rights of the Child in Islam (art 7); the 2012 ASEAN Human Rights Declaration (art 18).