§ 56 NDSG
Legal protection in the event of inactivity of the supervisory authority
(1)1Where the authority headed by the Land Commissioner for Data Protection does not deal with a complaint pursuant to § 55 or has not informed the complainant of the progress or the outcome of the complaint within three months of the lodging of the complaint, the complainant may take legal action against this. 2The provisions of § 20 of the Federal Data Protection Act and Article 78(2) of the General Data Protection Regulation shall apply mutatis mutandis in that regard.