I don't want to hear "she mighta said this, she mighta did that", I want to hear any possible justification for slamming a human head into the concrete. Any at all, Hypothe
When arresting a physically belligerent suspect, police are trained that the best way to deal with them is to put them on the ground. It is very hard for the suspect to attack the officer from that position and it affords the officer the most amount of control over that person with the least amount of force. Less force means both officer and suspect are less likely to be injured.
Ideally, that ground would be made from some spongy, soft material, or maybe even marshmallows. Unfortunately, most of the ground today is either covered in concrete or asphalt so when a suspect is taken to the ground, that ground, unfortunately, is someone harder than marshmallows.
It's not always practical to move a physically belligerent suspect to a mattress store or pillow warehouse in order to effect the arrest.
Perhaps in the future, a suspect might take this into account and only physically attack police in a place that affords softer ground on which they can be restrained.
That's wonderful background reading. And it doesn't touch the question.