The Photographer’s Right in Germany

After moving to Berlin, I became very cautious in street photography. People here are much stricter in their rights; you can see it e.g. in the street traffic: some might punish or even kill you if they see you crossing the street when the traffic light is red. In NYC I never feared that someone could destroy my camera, here I'm not sure. –
However, the official rights as a photographer are not clear for me. Everybody has a right, not to be photographed with exceptions. And here is the point: does "art" justify the exception? That's what a street photographer doing; it has nothing to do with marketing or advertisement; however street photographs might be published (exhibition, books, photoblogs, etc.).
In the US, The Photographer's Rights seemed to be clearer.
Does anybody know more?