The activity of a designated data protection officer according to Art. 39 DSGVO does not constitute a violation of the German Legal Services Act (RDG). This legal opinion of the BvD is also confirmed by the North Rhine-Westphalia Lawyers’ Court (ruling of 12.03.2021).
The reasoning in brief: Art. 39 DSGVO expressly includes legal advice on data protection. Accordingly, this is permissible under § 3 RDG due to admission in another law. Even if this were not so, this would constitute a permissible secondary activity within the meaning of § 5 RDG.