It seems that any physical beating by a person in authority is considered corporal punishment. This notion is incorrect. When manhandling takes place against innocent students or subordinates, it is an assault against an adult victim or rape of social and mental equanimity of young growing children.
Innocent children have no developed psychological defence mechanism against physical and verbal aggression by their guardians especially when these occur out of personal anger or vendetta.
To misuse official authority of any institution, office or school to victimize one's charges or subordinates in defence of one's erring family member could be construed as an act of criminal nature.
When something seemingly has gone haywire beyond doubt in an institution, the responsible next administrative authority has to take corrective measures immediately. The legal or judicial process can take time but the institutional administrative and social environment should be restored and freed of autocratic personality. Such responsive administering would curb future callousness and assuage the grievances of the victims.