Both, the European and the Austrian competition law have detached themselves from the enforcement by public authorities and have moved towards private enforcement. The tension between these two forms of enforcement is evident. On the one hand it is essential for the public enforcement of the competition law to have information from the leniency applicant available. To facilitate the cooperation with leniency applicant there is a need to protect the information they have. On the other hand private enforcement of the competition law, in case of action for damages, needs all essential pieces of information, so that the aggrieved party is able to rely on these. On European level, the current state of the case-law has to be criticized. Due to the fact that there are no conjectures in terms of the need of protection for the documents of the principal witnesses, the European Commission is forced to prove the need of the protection of every single document. A possible approach to finding a solution could be an analogous application of the conjectural rule, which already exists for the files of state-aid proceedings. In Austria the tension was resolved abstractly in favour of the effectiveness of the public enforcement of the competition law; access to case-files ? in particular to files of principal witnesses ? to a third party may only be granted with respect to the agreement with other parties. Because of the fact that each demand of a third party to get access to case-files has to be approached individually, it appears more than doubtful whether this conceptual regulation takes into account the provisions of the European Court of Justice. In addition, the Austrian law allows getting the files of principal witnesses indirectly, with the help of the administrative assistance by some other authority. In this context, the question arises whether this regulation is applied in case of administrative assistance. The case-law does not answer this question unitarily.