On 6 June 2013, the European Court of Justice ("ECJ") published its judgement in Donau Chemie (C-536/11). The case concerned a reference for a preliminary ruling brought before the Oberlandesgericht Wien (Higher Regional Court, Vienna), sitting as the Kartellgericht (Austrian Cartel Court ("ACC")). The question to the ECJ was whether a provision of national law that precludes the possibility of third party access to documents in the national court's cartel case file, absent the consent of the parties in that cartel case, is compatible with EU law.

The ACC had previously imposed fines on the members of a cartel on the Austrian market for the wholesale distribution of printing chemicals. An association of customers, ("VDM"), applied for access to the case file before the ACC. However, a provision of Austrian national law precluded third party access to the files of competition law proceedings absent the consent of all the parties to those proceedings. Since none of the parties except the Austrian Federal Cartel Authority ("FCA") gave consent for disclosure, the ACC had to withhold access to the file.

The ACC asked the ECJ whether the provision was compatible with EU law. The ECJ ruled that this was not the case. It referred to its previous judgements in Courage and Crehan (C-453/99), Manfredi (C-295/04), and Pfeiderer (C-360/09), where it had established that the national rules applicable to damages claims for EU law infringements should not be made practically impossible. The ECJ found that the national provisions must allow national courts to engage in a case-by-case balancing exercise of interests where a third party request for access to file is made. The Austrian provision did not allow for any balancing of interests, since access to the file could only be granted with the consent of the addressees of the decision. The ECJ noted that the public interest in an effective leniency programme should be balanced against the claimant's interest in disclosure and that this balancing act should be made for every single document of a case file. Therefore, the Austrian provision was in violation of European law.

In this case, therefore, the ECJ basically confirmed the principles it had established in Pfleiderer.