A law expert says a senior police officer disciplining his children with a belt is assault

The Independent Police Conduct Authority's found the North Island officer hit his three children on multiple occasions, by striking their lower body.

He admitted to using his belt to "re-set" his kids - he's been censured by Police for serious misconduct.

Auckland University Law Professor Mark Henaghan says criminal proceedings couldn't go ahead because neither the parent or the children would give evidence.

He says Liz Gunn was charged with assault for taping someone on the shoulder, and this is hitting kids with a belt and nothing's happened.