[yoo1I]

This is a common myth. There is no such thing as a "Beamtenbeleidigung" ("Insulting a civil Servant") in German law. Insulting a cop is handled by the same laws as insulting everyone else. It's just that public prosecutors will be more likely to actually criminally prosecute, instead of deferring the insulted party to a civil suit on the matter.

[Mithaldu]

That's not a very great explanation of it. In the base of it, insulting someone breaks StGB §185 and a lawsuit over it can be initated by a civilian as per StPO §374. Civil servants are different because their superiors have the ability to sue in their stead as per StGB §77a.

http://dejure.org/gesetze/StGB/185.html - http://dejure.org/gesetze/StPO/374.html - http://dejure.org/gesetze/StGB/77a.html