The use of private detectives for the surveillance of the employee is justified due to the encroachment on the right of personality of the observed person, which is protected by Art. 2 para. 1 in conjunction with. Article 1 (1) of the German Basic Law, the use of private detectives to monitor the employee is only justified if concrete facts justify the suspicion that the employee has committed or is committing a criminal offense or significant breaches of contract. In addition, the use of detectives is subject to a justification and proportionality test and the requirements of data protection law.
During the observation of an employee by a private investigator, the latter processes personal data within the meaning of Section 26 BDSG. Due to the necessary secrecy of the surveillance, the employee's consent to the processing is out of the question, so that there is rather a serious encroachment on the right of personality protected by Art. 2 (1) in conjunction with Art. 1 (1) GG. Article 1 (1) of the German Basic Law, the right to respect for private life under Article 8 (1) of the European Convention on Human Rights and, in the case of photographs, the right to the employee's own image. Such observations are therefore only permissible if they are justified. Justification may arise from Section 26 (1) sentence 2 BDSG and/or from Section 26 (1) sentence 1 BDSG.
Section 26 (1) sentence 2 BDSG stipulates that personal data of an employee may only be processed for the purpose of uncovering criminal offenses "if factual indications to be documented justify the suspicion that the data subject has committed a criminal offense in the employment relationship, the processing is necessary for the uncovering and the interest of the employee worthy of protection in the exclusion of the processing does not prevail, in particular the type and extent are not disproportionate with regard to the reason. "If there is no possible criminal offense, but the employee has committed significant breaches of contract, the BAG has ruled that data processing can also be justified by Section 26 (1) sentence 1 BDSG. According to this, data processing in the case of serious breaches of duty that do not yet constitute a criminal offense is justified for purposes of the employment relationship if it is necessary for the decision "on the establishment of an employment relationship or, after the establishment of the employment relationship, for its implementation or termination".
In both cases, the concrete suspicion must be based on factual and objectifiable indications that already existed before the detective assignment. According to the case law of the BAG (ruling of October 20, 2016 - 2 AZR 395/15), an initial suspicion within the meaning of Section 152 (2) of the German Code of Criminal Procedure (StPO) against a definable group of employees is sufficient for this. Such a case exists if an employee announces his incapacity to work to colleagues in advance (LAG Hamm, July 22, 2004 - 8 Sa 478/04).
If there are concrete facts or demonstrable reasonable doubts as to the existence of a criminal offense or a serious breach of duty, the deployment is still subject to a justification and proportionality test. The observation must be suitable to prove the criminal act or breach of duty and there must be no other, milder means of proof available. Thus, the facts of the case must first be clarified, for example, by interviewing witnesses, narrowing down the employees under consideration, hearing the employee and similar milder measures. In addition, justification for the observation exists only for the degree of restriction(s) required by the evidence. Observation conducted for the purpose of proving "sick leave" and lasting more than 14 days exceeds such a degree. Observation in and from private rooms is always excluded due to the affected core area of the employee's private sphere and is punishable under Section 123 (1) of the Criminal Code and/or Section 201a (1) No. 1 of the Criminal Code.
If employees are monitored by means of technical equipment, this also triggers a right of co-determination for the works council pursuant to Section 87 (1) No. 6 BetrVG, which in practice can only be prevented by excluding the use of technical equipment.
The employer bears the burden of proof for the existence of a breach of duty in the context of proceedings for protection against dismissal. Unauthorized observation does not necessarily lead to a prohibition on the use of evidence in the proceedings. However, case law derives a prohibition on the use of evidence from a violation of the employee's general right to privacy if the use of the evidence perpetuates the infringement of fundamental rights. Thus, the court must examine in each individual case whether the use of the illegally obtained evidence is compatible with the employee's right of personality or establishes the impermissible encroachment.
If the detective assignment is not carried out in accordance with the requirements described, the employer can expect substantial fines or even criminal prosecution. The employee may also be entitled to claim damages. Due to these risks, a concrete, individual case examination and qualitative selection of a private detective is mandatory in every case. In particular, the core question will always be whether the observation is proportionate with regard to the suspicion to be investigated.
Finally, the employer must comply with the obligation to delete data. In particular, the data must be deleted immediately if its processing is unlawful, if it is no longer necessary for the purposes for which it was collected or otherwise processed, or if interests of the data subjects worthy of protection conflict with further storage. However, the storage of the collected data remains proportionate as long as legal prosecution by the employer is possible under substantive law. ("Data protection is not deed protection", BAG dated August 23, 2018 - 2 AZR 133/18).