Article L741-6 of the French Code governing the entry and residence of foreign nationals and the right of asylum
The decision to place the foreign national in detention is taken by the administrative authority, after the foreign national has been questioned or, where applicable, during his detention for the purposes of verifying his right to move or reside, at the end of his police custody, or at the end of his period of incarceration in the case of detention. It shall be in writing and state the reasons on…