With the third-party effect of trade union freedom of association under Article 9 (3) sentence 1 of the Basic Law on the employer's domiciliary rights, the study sheds light on a potentially particularly conflict-laden relationship between the social partners, which is likely to gain considerable importance in future legal practice. The study shows that in order to solve the problem, it is imperative to draw on the findings of fundamental rights doctrine on Article 9 (3) sentence 1 of the Basic Law, the observance of which leads to far-reaching modifications of the solution to the conflict provided for in simple law. In this context, problems of the enforcement of rights and consequences in labour procedural law due to the third-party effect of Article 9 (3) sentence 1 GG are also highlighted.