Access to citizenship in Mauritania is governed by the Loi N° 1961-112 portant code de la nationalité mauritanienne as modified most recently by Loi No 2010 – 023 and Loi No. 2021-016. The 2010 amendments removed provisions that attributed nationality automatically to a child born in Mauritania of a parent who was also born there (with the right to repudiate at majority if it was only the mother who was also born there). The 2010 law also altered the provision for access to nationality of women married to Mauritanian men from automatic recognition to requiring an application process. There is still no provision for the husbands of Mauritanian women to acquire nationality, and women cannot transmit nationality to their children born outside the country. In 2021, the law was further amended to permit dual nationality.
A critical issue related to citizenship in Mauritania has been the treatment of Mauritanians of black African descent. Mauritania is populated by three principal groups: lighter-skinned people of mixed Arab-Berber heritage, known as Beydanes; Arabic-speaking darker-skinned people known as Haratines, the descendants of former slaves; and those belonging to sub-Saharan ethnic groups, speaking a range of other languages. From the mid-1980s, the Mauritanian government undertook a policy of Arabisation, increasingly discriminating against non-Arabic speaking Mauritanians. In 1989, following a dispute between Senegalese farmers and Mauritanian pastoralists in the Senegal River Valley, an estimated 70,000-80,000 black Mauritanians were expelled to Senegal and Mali.
In 2005, a change in government opened the door to repatriation to Mauritania and approximately 25,000 Mauritanians returned with UNHCR assistance between 2008 and 2012. However, the returnees complain that they have been unable to access lost land or identity cards, and face ongoing discrimination. The introduction of a new identification system in 2010, in parallel with amendments to the nationality code, left many who claimed Mauritanian nationality unable to access new identity cards.