2. In the cases referred to in paragraph 1, the controller shall inform the data subject, without undue delay, in writing of any refusal or restriction of access and of the reasons for the refusal or the restriction. Such information may be omitted where the provision thereof would undermine a purpose under paragraph 1. The controller shall inform the data subject of the possibility of lodging a complaint with the European Data Protection Supervisor or of seeking a judicial remedy before the Court of Justice. The controller shall document the factual or legal reasons on which the decision is based. That information shall be made available to the European Data Protection Supervisor on request.