I'd like to clarify 3 things:
As long as none of your beloved getting hurt...
But in the end you are behaving like a ignorant piece of something. Because people all around are starting to suffer by this dirtbags and then calling for endless liberalism is just as stupid as damning all immigrants.
People like you are what makes a big anti-islamic movement necessary.
You're an idiot and you obviously didn't read the thread, especially not my recent posts. Go away.
Then Torben wrote that there is no way to send refugees away after committing a crime. That statement is not entirely true. The hurdle is just very high. Too high in my opinion.
The State is allowed to deport an immigrant/refugee if he/she commits a crime that is punished with 3 years jail time or more. Certainly should be lower and should include certain k.o. criterias which allow instant refusal of the current status of immigration and instant deportation (e.g. rape, paedophilia and similar stuff).
Then Tibe wrote about self-defence laws in Northern countries. Probably not meaning Germany directly but I do feel that German laws are okay.
When you are attacked, you are allowed to defend your life and health with adequate force.
When you witness a crime, you are allowed to temporarily fixate the criminal until the police arrives with adequate force. It's the so called "Jedermanns Recht" ("Everybody's right").
Tho the interpretation of adequate force is something you could stumble over.
Starting with the easier case of fixation of a criminal. Adequate force means here that you are allowed to use force to hold the guy down. You don't wanna hit him tho. Imagine it as a grappling match, wrestling of sorts. Punching is bad. You might get lucky and nobody says anything with just 1 hit, like stop him from running away. But that's it. Still, it's reasonable. It's not your job to hunt him down anyway. You get a chance to grab him - fine. Everything else is the police's job.
I know several people, working the door of clubs, who got into issues with the law in this department but in 90% it's okay. You have to overdo it quite a lot to get into trouble.
Now, threat to life and health is tricky. And it would take too long to describe properly but let me say this much: killing the attacker is always very bad news cuz it's hard to verify the "I had no choice." Even breaking limbs is a problem.
And then there is a big differentiation between trained and untrained people. Untrained people are basically okay to use more force while trained people are granted lower reaction times for affect for example.