Unannounced audits – legally permissible as a general rule?

According to Section 25 (1) GenTG, the competent authorities must monitor the implementation of the legal basis and the official orders and rulings based thereon. To this end, the operator, the PL and the BBS must, according to Section 25 (2) GenTG, immediately provide the authority with the information required for monitoring upon request and make available the necessary resources, including control samples, within the scope of their availability. According to Section 25 (3) GenTG, the authority is authorized to enter and inspect the premises during business hours, to carry out all tests necessary to fulfill its duties, including taking samples, and to inspect the documents required to fulfill its duties and to make photocopies or transcripts thereof. At the same time, the operator, the BBS and the PL are obliged to tolerate and support these measures (Section 25 (3) Sentence 3 GenTG), the latter to the extent necessary to fulfill their duties, and to submit the necessary business documents. The operator's obligation to tolerate inspections and visits is immediate and can be enforced by the authority, if necessary, even without prior notice. However, for reasons of proportionality, the authority will generally be required to give the operator advance notice of its request for access and inspection. The supervisory authority's request for information is a contestable administrative act. The same applies to the request to submit certain documents. There is no specific form prescribed for the request; it can be made verbally, in writing, or in another way (Section 37 (2) Sentence 1 of the Administrative Procedure Act) (for the parallel provision of Section 52 of the Federal Immission Control Act, see Hansmann/Röckinghausen, in: Landmann/Rohmer, Environmental Law, Vol. III, Commentary, as of July 1, 2018; 87th supplement, Section 52 of the Federal Immission Control Act, marginal no. 48 with further references). This is because the operator must ensure access to the facility and submit the necessary documents. In this respect, the supervisory authority will also have to specifically communicate which facility and which documents it intends to inspect. The operator must be given sufficient time to organize the inspection and provide the necessary documents. However, if irregularities have occurred during previous inspections, the inspection may also be conducted unannounced (exceptional).