Regulatory law is a cross-cutting subject that contains elements of both legal systems - public law and private law. The conclusion and enforcement of civil law infrastructure usage contracts are regulated by the Federal Network Agency. In this context, the distinction between the two legal systems is not only relevant in terms of the legal path to be taken, but also in the application of the law. For instance, when interpreting regulatory legal norms, civil and public law approaches compete with each other. This work illustrates this with practical examples and presents potential solutions.