Until the Second World War, the grant and withdrawal of nationality was regarded as being wholly within the sovereign discretion of states. Since the Universal Declaration on Human Rights first provided for the right to a nationality in 1948, the international human rights framework has increasingly restricted that discretion.
The 1954 Convention relating to the Status of Stateless Persons provides for the protection of stateless persons in a similar framework to that established for refugees; while the 1961 Convention on the Reduction of Statelessness establishes certain basic rules to avoid statelessness at birth and in case of loss or deprivation of nationality.
The International Covenant on Civil and Political Rights and the Convention on the Rights of the Child, both provide for every child to have the right to acquire a nationality. In addition, all the international human rights treaties targeting various forms of discrimination mention the right to a nationality, including the Convention on the Elimination of All Forms of Discrimination Against Women, the Convention on the Elimination of All Forms of Racism, the Convention on the Rights of All Migrant Workers and Members of their Families, and the Convention on the Rights of All Persons with Disabilities.
More information on the international standards and actions against statelessness can be found on the UNHCR website, including a set of important Guidelines on Statelessness and Good Practices Papers for states. In 2014, UNHCR launched the #IBelong campaign to end statelessness in ten years.