Law n° 51-711 of 7 June 1951 on obligations, co-ordination and confidentiality in respect of statistics. Available from https://www.legifrance.gouv.fr/affichTexte.do?cidTexte=JORFTEXT000000888573.

Article 6 concerns statistical confidentiality: Subject to the provisions of Articles 40, 56, 76, 97 and 99 of the Code of Criminal Procedure and those of Article L. 213-3 of the French Heritage Code, the individual information contained in the questionnaires endorsed as provided for in Article 2 of this Law and relating to private and family life and, in general, to private acts and conduct can not, unless decided by the Archives Administration, after examining the opinion of the Statistical Confidentiality Committee and relating to a request made for the purposes of public statistics or scientific or historical research, be the subject of any communication by the depositary service before the expiry of a period of seventy-five years following the date of completion of the survey or a period of twenty-five years from the death of the person concerned, whichever is the shorter.
A Statistical Confidentiality Committee is set up. This committee is called upon to rule on any question relating to the confidentiality of statistics. It expresses its opinion on requests for the communication of individual data collected pursuant to this law. The committee is chaired by a State Councillor, appointed by the Vice-President of the Council of State. It includes in particular representatives of the French National Assembly and Senate. The composition and operating methods of the committee are set by decree of the Council of State. Recipients of the data communications resulting from Ministerial decisions made after consulting the Statistical Confidentiality Committee agree to not communicate these data to anyone. Any violation of the provisions of this paragraph is punishable by the penalties provided for in Article 226-13 of the Penal Code.

Regarding Internet collection, the collection site is completely secure and the standards in terms of managing access codes to the survey are strict. For companies choosing to use paper, the data entry is ensured by the managers, in strict respect of the confidentiality of the data collected.
Before the dissemination of the data the secrecy is applied. For enterprise data: no results are published for less than three enterprises or establishments. Similarly, a result will only be released if no company or institution contributes more than 85% of that result. Thus the so-called primary secret corresponds to the boxes meeting the above criterion. The secondary secret removes other boxes so that the data cannot be retrieved by subtraction with the margins of the tables. Statistical confidentiality is defined in Act No. 51-711 of 7 June 1951.