The hearing takes place at the end of the investigation procedure, which ends with the briefs in response to the report. In this phase the parties present their oral observations before the Authority deliberates and adopts its decision. The Competition Authority summons the parties to a hearing by way of registered letter sent at least three weeks prior to the date thereof (Commercial Code, Art. R. 464-6). Hearings before the  Authority are not public – only the parties to the action and the Commissaire du Gouvernement (government commissioner) may attend (Art. L. 463-7 Commercial Code). The president of the hearing will call upon, in order: the rapporteur(s), the rapporteur general, the government commissioner and, finally, when present or represented, the parties having asked to be heard. The Authority may also hear any person whose testimony it considers likely to contribute to its understanding: in such cases, this person or persons are brought into the chamber and heard separately, in the presence of the parties, and may then be questioned in each others’ presence. The adversarial nature of the proceedings is such that the parties and their counsel are entitled to be informed of the identity and occupation of any witnesses to be heard by the Authority. They also have the right to request the Authority hear the testimony of other witnesses.

The rapporteur general and his/her deputies, the rapporteur having handled the case and the Commissaire du Gouvernement may also submit their observations. During the session, the rapporteurs are not required to put forward the exact same opinion as set out in their report and are free to change their assessment of the facts on condition that no factor absent from the file is alleged against the respondents and that the latter have a right of reply in conformity with the adversarial principle. Where the rapporteur raises new matters in the session, the Competition Authority is not obliged to reopen the debates to allow undertakings to address them but may prefer to allow them to draft a post-hearing submission. In that case, the adversarial principle precludes the Authority from imposing an overly short deadline for their submission or from placing a limit on the points they may raise. The Authority may not take a decision on the basis of the post-hearing submission without having previously disclosed it to the other parties in proceedings.