Interesting Question - I suspect the penalty would be far more than if the shoe was on the other foot.
I would like to know what powers police have to use the asp in general. I suspect the police could call just about anything "fear for personal safety of themselves or others"
I know someone who was breaking up a fight outside a bar. Police arrived and he was dragged away and told to get face down on the pavement. He refused and tried to explain he was breaking up the fight, so the policeman pulled out the asp and struck him in the leg once then 2 more times when he was on the ground. He had black and yellow bruises from the buttock to the knee (photographed of course). He was arrested and bailed pending evidence from CCTV. The policeman claimed that he was punching and kicking someone lying on their back and that he threw punches at the police prompting the asp. Sure enough, CCTV proved that he was merely trying to break up the fight and there was no further action.
What penalty could a policeman receive, firstly for supplying a statement which grossly contradicted the evidence from CCTV and secondly, using an asp when someone is on the ground?