interference with (fundamental) rights is a sphere of action that is reserved to statute.
* The principle of legal security, which includes a principle of legal certainty and the principle of non-retroactivity.
* The principle of proportionality, which means that an act of an authority has to be suitable, necessary and appropriate.

The vast majority of public administration in Germany is performed by its component federal entities , which are responsible for the execution both of federal laws and their own laws (execution of