French citizens and headquartered corporations cannot answer a foreign justice request concerning some things (pretty much everything as the wording is vague) without refering it first to the french government. Failing to do so exposes to fines and possibily jail.
https://www.legifrance.gouv.fr/loda/id/JORFTEXT000000501326/...
"Loi n° 68-678 du 26 juillet 1968 relative à la communication de documents et renseignements d'ordre économique, commercial, industriel, financier ou technique à des personnes physiques ou morales étrangères"