0 points
The police can shut down any protest, if it was not filed for in advance. Unless of course you protest with a tractor. The police is powerless against tractors. The hierarchy in Germany is therefore:
Tractor > Bureaucracy > Police > You and Me
1 point
You have to register at a certain expected size so police can have enough policemen on site to be able to keep public order. There are very few cases where these applications have been denied and with good reason. Demonstrations are only dissolved if they get too unruly and dangerous for the public.