Beating on children is a crime, regardless of whether or not you dress in blue or wear a badge. When police are guilty of assault, manslaughter, murder or child abuse, they should be arrested, tried and sentenced for their crimes. The rule of law applies, regardless of what a partisan Supreme Court may presume. Hired peace-officers work to protect and serve the people who hired them, and those who enforce the law must also obey and observe the same laws. It's in the book. 

When we allow beating on helpless children, we can more easily dismiss murdering unarmed citizens in street executions, and ignore or deny our export of terror, munitions and war, spending trillions to kill millions for billionaires who pay no taxes.  Lesser-evils, wars for profit, unprovoked aggression, trickle-down lies, destruction, debasement, dishonor, avoidable wars, needless drones and presidential murders without due process of law are illegal, unconstitutional and unacceptable.