Police need to use something similar to the UCMJ (Uniform Code of Military Justice) that the military abides by. This article eloquently explains this better than I can.
"If we are willing to provide military equipment and training to our local law enforcement, let us also share their higher standards of behavior with police. "
I was in a dollar store the other day that had 2 GIANT posters on the front doors saying “NO CASH” “We cannot accept cash payments at this time” and while I was in there I saw 3 people get told they can’t accept cash and then the shoppers left the store in a huff.