Article L813-5 of the French Code governing the entry and residence of foreign nationals and the right of asylum
A foreign national who is notified that he or she is to be detained pursuant to article L. 813-1 shall immediately be informed by the judicial police officer or, under the latter’s supervision, by the judicial police agent, in a language that he or she understands or can reasonably be presumed to understand, of the reasons for his or her detention, the maximum duration of the measure and the fact…