My thought on this is that it's basically not legal to protect your home/family with force because of this. It's impossible to know if someone breaking in is a cop or not, and at 3AM with glass breaking and a group of people claiming to be cops, but aren't, how are you supposed to know? You basically never can. So either you risk going to prison for the rest of your life when it's actually a cop, or you do absolutely nothing and let your family get harmed/your home burgled.