So we should forbid firefighter and farmer's union ? And all leftist union ? And we should forbid any protest where people using black block technique could agree with ?
In France, in most of the cases you don't need police officer for it, some people are willing to donage bank or fight with the police (especially after police overreacting, or being violent for free)
The fact is you don't know how will end up protest... And even when a protest end up damaging 1 mac donalds and 2 banks, most people are pacific protester... The question is how do you handle this in a democracy ?
