They don't, or rather aren't supposed to, commit crimes to catch criminals. The laws are written with verbiage indicating who can and can't do what and under wh

They don't, or rather aren't supposed to, commit crimes to catch criminals. The laws are written with verbiage indicating who can and can't do what and under what circumstances. There is no real law that just simply states "thou shall not kill" that applies to everyone in every role in every situation. And even if law were equal to ethics, I don't think most people hold ethics without exceptions to whatever general descriptions they use to communicate them.