Hearings may, as is the case in European law, be conducted at different stages of the competition proceedings.

Firstly, when the Competition Authority initiates a basic investigation, the authorized officials have the power to gather information and evidence on the spot or upon request. Where statements are not obtained fairly, they are removed from the proceedings, without it being necessary to show that the person concerned has suffered any particular prejudice. Similarly, in the event of a court-ordered investigation, the authorized officials may, during the course of the visit, interview the occupant of the premises or his or her representative in order to obtain any information or explanations that may be useful for the purposes of the investigation.

Secondly, if necessary, the rapporteur may hear the undertakings during the preparatory phase (Commercial Code, Art. L. 450-1). The rapporteur is not obliged to hear the parties involved in the investigation, as the representatives of the undertakings are able to submit written observations to the Statement of Objections and to develop them orally at the hearing before the Authority. Furthermore, the rapporteur is not required to hear the parties at the same time as the persons who having made the statements implicating them, nor to question them about the contentious documents seized from third parties. However, at the time of the hearing, he or she must inform them of the general context in which the hearing is being held. The hearings are recorded in minutes, which may take the form of e-mails, even if they do not reproduce the questions asked. However, they must make it possible to establish the origin, accuracy and validity of the communications in question.

After the Statement of Objections has been issued, Articles L. 463-1 and L. 463-2 of the Commercial Code require the rapporteur who wishes to conduct hearings to summon by letter, prior to the hearing, the directors of the undertakings that he wishes to hear, and to inform them of the possibility of being assisted by a lawyer. While the rapporteur is not obliged to hear all the parties during the investigation, he may invite any person whose hearing he considers likely to contribute to providing information, including the lawyers of an undertaking referred but which is not a party to the proceedings. Minutes are drawn up of the hearings and must be signed by the persons heard. If they refuse to sign, this is noted in the minutes (Commercial Code, Art. R. 463-6). In addition, failure to respect the rights of the defense implies the removal of documents from the proceedings, in this case the minutes of the hearing. This deletion only leads to the nullity of the proceedings insofar as it has an impact on the proof of the anticompetitive practice.

Finally, the parties may be heard during the proceedings at the Authority. They are authorized to be represented or assisted. The Authority may hear any person whose testimony it deems likely to contribute to its knowledge (Article L. 463-7, paragraph 2). However, in order to respect the principle of adversarial proceedings and the rights of the defense, the parties or their representatives must be informed in advance of the hearing of the names and standing of the witnesses whom the Authority intends to call. Similarly, the parties must be able to ask the Authority, at its discretion, to hear other witnesses. The Authority is not required by law to transcribe the hearings of witnesses that it conducts in session. These hearings are not likely to infringe on the rights of the defense since they take place during the adversarial proceedings and the parties may ask the Court of Appeal hearing an appeal to repeat them in accordance with Articles 204 et seq. of the Code of Civil Procedure. When the Competition Authority has observed the adversarial principle, it is not required to justify that it has given the undertaking sufficient time to present its oral observations during the hearing.