Not too sure of any cases myself, but the honest truth is i've seen staff banning a lot more for what they think is wrong or should be (unwritten rules) against the rules rather than what is actually against the rules.
Question for you though - Why are police not allowed to issue warning shots which are much easier to do in a gunfight? As i'm sure you know there aren't loads of police at the start of a gunfight usually and it is hard to spare one. Why are there different methods?
If rebels can tell a heli to...
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From a recent report (can't properly quote as i'm on my phone) which states that knocking someone out with a gun pointed is a "clear cut" rule break despite not being a rule.
I'm sure you can see where i'm coming from when I say that people are threatened with and banned for unwritten rules...
In real life, the British Army would be called in to deal with robbers and not some underarmed police force. It also levels the gameplay and makes it less easy for rebels to rob the Treasury (which is very easy imo, i've seen it done with less than 5 people).