(1) The appellate court shall, acting ex officio, investigate the facts.
(2) The presiding judge shall endeavour to ensure that formal defects are eliminated, unclear motions are explained, relevant motions are made, insufficient factual information is completed, and all declarations essential for ascertaining and assessing the facts are made.
(3) The appellate court may direct the parties to file statements within a specified time on issues requiring clarification, to specify evidence, and to submit documents as well as other evidence in their possession. In the event of failure to observe the time limit, a decision may be made on the basis of the established facts without consideration of evidence which has not been produced.
(4) If a request pursuant to Section 59(5) or an order pursuant to Section 59a(5) is challenged by way of appeal, the competition authority shall substantiate the factual aspects. Section 294(1) of the German Code of Civil Procedure shall be applicable. No substantiation shall be required insofar as Section 20 presupposes that undertakings are dependent on undertakings in such a way that sufficient or reasonable alternatives of switching to other undertakings do not exist.
(5) The Federal Court of Justice may obtain an opinion from the Monopolies Commission in proceedings pursuant to Section 73(5).