In this clip from the film Lawman, Burt Lancaster tells it just as it is.  What is a lawman?  A lawman is a killer of men.

Indeed the difference between anyone of us and a police officer is that an officer has been empowered by the state to take life.  That officer is also empowered to confiscate private property and to deny citizens liberty.  That is the plain truth of it.  Officers are not allowed to act indiscriminately, there are rules. However, when officers are involved in a homicide, they are given wide latitude because killers of men are who they are.