The most prevalent United Nations legal instrument that has significantly affected immigration law and policy is the Convention Relating to the Status of Refugees, (1951) and its accompanying Protocol of 1967. The Convention sets out the international law framework on the recognition of refugees and the responsibility of States towards them. Many countries have legal mechanisms in place to recognise individual rights under the Convention and a number of States have enacted legislation explicitly recognising the primacy of the Convention.

Article 1 of the 1951 Convention defines refugees as people outside their country of nationality, who cannot return there due to a well-founded fear of being persecuted for reasons of race, religion, nationality, or membership of a particular social group or political opinion. Article 33 of the Convention prohibits the expulsion or return (refoulement) of refugees by States in any manner to the territories where their life or freedom would be threatened on the above grounds. The only exceptions to this provision are on the grounds of national security or public order, in pursuance of a decision reached in accordance with due process of law. The 1951 Convention also includes in the second, third and fourth Chapters, provisions on juridical status, gainful employment and welfare: including housing and public education.

The Convention Against Torture and other Cruel, Inhuman or Degrading Treatment or Punishment, (1984), Article 3, prohibits the expulsion, return or extradition of any person to another State where there are substantial grounds for believing that they would be in danger of being subjected to torture. In determining whether these grounds exists the competent authorities should take into account relevant considerations such as the existence in the State concerned of a consistent pattern of gross, flagrant or mass violations of human rights. The Convention in Article 1 defines torture as including "an act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as obtaining from him for a third person information or a confession, punishing him for an act he or a third person has committed or is suspected of having committed…or for any reason based on discrimination of any kind…" As with the 1951 Convention the Convention Against Torture has in some countries been incorporated into national legislation.

Article 23(1) of the International Covenant on Civil and Political Rights, 1966 guarantees protection of the family by society and the State. It prohibits arbitrary or unlawful interference with the family and requires administrative, legislative and other measures of protection. This provision is not limited by nationality or status and would therefore apply to migrants living in a State other than their State of nationality. However in line with the interpretation of other parallel provisions in international law this does not mean that migrants would be guaranteed the right to choose where, that is in which country, to establish their family. If the family could be protected in a country other than their country preference they may have no other choice than to reside there.

The International Convention on the Protection of the Rights of all Migrant Workers and Members of their Families, 1990 would protect migrant workers engaged in employment in a State of which they are not national, this would include irregular migrant workers (see paragraph 8.5). There is however no right under UN law to migrate for the purposes of employment.

Analysis provided by: Anisa Niaz LLM (Public Law), United Kingdom.