Well for that matter, how can we tell if any particular LEO is a felon or a nut bag? They do exist, and when we encounter one we have a helluva lot less options available to us, than when a LEO encounters one. Freedom means having to deal with such occasional problems. Prisons mean not having to deal with them. Liberals can't tell the difference, and don't want to.
Two words: (names) Erek Balentine...
Very well stated. Plus it is perhaps helpful to remember the R. A. Heinlein quote:
“an armed society is a polite society.”
I’ve been reading a lot of Louis L’Amour lately, and lawmen did have to deal with armed criminals and it can be done.... very politely!