This study is about the political regime in Mauritania, especially with regards to the preponderant influence of French law on this regime – a strong influence on the state’s central administration and on decentralized local administration, as well as on the whole of the political institutions.The first Mauritanian constitution of March 22, 1959 was directly inspired by the Constitution of the Fifth French Republic of October 4, 1958 – and the setup of a democraticregime « à la française », a « rule of law » with a separation of powers. However, this influence of French law on the Mauritanian political regime remains limited, for political,cultural, economic, religious, and social reasons. Several difficulties related to the adaptation of French law by the regime, and consideration of specificities of Mauritanian society, have been raised in this study. Indeed, no « rule of law » can be constituted without the unconditional respect of all human rights, and without applying the principle of equality,independence of the judiciary, and transparency in matters of public services.The Mauritanian political regime, while very influenced by the values andfundamental principles of French law, remains an ensemble of rules of Islamic origin and of« Sharia law », like most Arab and Muslim countries.