Cops can do whatever they want.  Chances are they WILL get away with it.  If they are fired or suspended, it's usually overturned on appeal.  If they kill someone unjustifiably, in the rare times that it actually goes to criminal court juries will usually find them not guilty.

If the city settles a civil action, the taxpayers get stuck with the tab.

If that's not a license to kill and break the law I don't know what is.