Adjudication within a reasonable time is an essential requirement in competition proceedings. According to a general principle of European law enshrined in Article 6 ECHR and repeated in Articles 41 and 47 of the Charter of Fundamental Rights of the Union, the Commission must adopt its decision within a reasonable time. The assessment of reasonableness is made in the light of the circumstances specific to each case: complexity of the case, conduct of the parties or the competent authorities, what is at stake for the various parties, number of leniency applications, number of successive court proceedings, translation difficulties, complexity of certain legal issues. These criteria are alternative. It is sufficient for the duration to appear reasonable with regard to only one of them for the procedure to be declared valid.

To determine a possible adverse effect on the rights of defense resulting from an excessive duration, the EU court takes account of all procedural steps preceding the Statement of Objections. Failure to comply with the principle that the Commission must act within a reasonable time cannot affect the validity of the administrative procedure where it does not affect the rights of defense of the undertakings concerned. The Court of Justice has held that in view of the need to enforce the Union’s competition rules, the mere failure to respect a reasonable period must not enable the appellant party to undermine the validity or the amount of a fine where all the arguments against the findings of the court have been rejected.

Where an appeal is lodged against a Commission decision, the European court must also examine it within a reasonable period of time. The breach of this obligation has, as with Commission decisions, no impact on the amount of the fine. In such a case, the parties must bring an action for damages, not before the Court of Justice in the context of the appeal, but before the General Court itself, which will rule in a different bench from the one in which the case was heard. A period of fifteen months between the end of the written phase and the opening of the oral phase of the proceedings, possibly extended by one month for each additional related case examined, is in principle an appropriate period for dealing with cases concerning the application of competition law. Beyond such a time-limit, the victim undertaking may obtain damages for the loss suffered as a result of bank guarantee fees incurred during the period deemed excessive and for the non-material damage resulting from the unusual level of uncertainty in which it was placed.