The cop ABSOLUTELY has the fucking responsibility to punch people if they are instigating violence you nitwit. It's exactly why we pay them. I see no ethical problems with a police officer punching someone who starts a fight with them. I understand why some people may this the amount of force displayed here is perhaps too much, however in this particular situation, the officer was completely alone, and if the suspect had a knife or gun and was trying to reach for it, the officer was fighting for their life. Also, if the suspect was able to knock down the officer, they could take the officers gun and kill them. If there were 2 or more cops present and an officer was acting like that I would agree its too much force.