Imagine someone is in a park playing music on his boombox. A police officer tells him to stop but he does not comply. The police confiscates the boombox, and then the guy decides to be a smart ass and starts singing the music. What should the police officer do next? If he does nothing this will not be fair to the people who do comply. So the police must keep escalating the amount of force he uses, up to and including terminating the person's life, until the person complies. If at any point the police stops trying and leaves the person alone, this is just rewarding who have above a certain threshold of stubbornness. This is why more often than not police justified in escalating their use of force, even when the initial crime was small.