The Commission has the power to hear undertakings in two phases of the competition procedure: during the preliminary investigation and after the Statement of Objections during the administrative procedure.

During the preliminary investigation, Regulation No 1/2003 grants the Commission the power to take statements (Article 19). The Commission may interview any natural or legal person who agrees to be interviewed for the purpose of collecting information relating to the subject matter of an investigation. Where statements are taken at the premises of an undertaking, the Commission must inform the competition authority of the Member State in whose territory the interview takes place. The officials of the Competition Authority of the Member State concerned may, if the Commission so requests, assist the officials, and other persons accompanying them, authorized by the Commission to conduct the interview.

Respect for the rights of the defense then requires that each undertaking or association of undertakings concerned be given the opportunity to be heard on the objections which the Commission intends to uphold in the final decision. The right to be heard implies that the undertakings concerned must be given the opportunity to submit not only written but also oral observations. The Commission may therefore organize hearings to supplement the written phase of the procedure. Hearings are not, however, always used. The undertakings and persons concerned – parties, addressees of the objections (Regulation No 773/2004, Article 12), complainants (Regulation No 773/2004, Article 6) or third parties who can show a sufficient interest (Regulation No 773/2004, Article 13) – must make a request in their written observations. The Commission may also give any other person the opportunity to express his or her views orally.

The Commission has a reasonable margin of discretion to decide how expedient it may be to hear persons. The interest in being heard may result, in particular, from the complexity of the facts or the legal issues. In practice, the Commission tends to recognize such an interest whenever it considers prohibiting an agreement or practice under Articles 101 and 102 TFEU.

A new hearing is not required when the Commission investigates a file the procedural measures of which have not been affected by the annulment of a previous decision. On the other hand, where the prior decision is annulled for lack of authentication, a new hearing of the undertakings is necessary where the annulled decision has been made without those undertakings accessing the whole file and properly exercising their rights. This is also the case where, after the entry into force of Regulation No 1/2003, the Commission adopts a new decision after the annulment of a previous decision adopted on the basis of the ECSC Treaty; it is then necessary to arrange new hearings in the presence of the competition authorities of the Member States.

The hearings during the administrative procedure are conducted by the Hearing Officer.