It clear with the Zimmerman case, You dont seem to know the basic Facts
There is a law in many states that if an intruder breaks into your home you are allowed to use deadly force.
Many States including Florida has expanded this to Citizens Patrol groups (Like the Shomrim) who are not cops, but patrol neighborhoods. The Law is called STAND YOUR GROUND.
Zimmerman was on this “Citizens Patrol” and Saw Mr Martin wearing a Hoodie and felt he was a Perp and tried to “Apprehend” him.
Exactly what happend next is up for debate, except the Zimmerman killed Treyvor Martin. His defense was the STAND YOUR GROUND law.
Obviously it was a mistake and Martin was killed. If Zimmerman tried to Apprehen Martin and martin fought back it was Self Defense by MARTIN as you cant arrest someone for not doing anything.
Consider it like someone gives you some food and you eat it anfd you find out later it wasnt Kosher, Whose fault was it?
Obviosuly you are supposed to make 100% sure it was kosher before eating it.
This was worse because someone was killed, Someone was killed by mistake , There are no mulligans in murder.
And BTW the author of the Stand you Ground Law says this case does NOT apply in this case as the Stand your ground only applies AFTER you call 911 which Zimmerman did not