The New Zealand Animal Law Association says it has filed criminal charges against a rodeo cowboy for using an electric shocker on calves and cattle at Northland rodeo events.

A statement from the association says the events were captured in footage broadcast on Checkpoint with John Campbell and this was investigated in 2017 by the Ministry for Primary Industries.

"The investigator confirmed that criminal offences had been committed and recommended a prosecution. However, MPI eventually decided not to prosecute and issued a warning to the defendant," it says.

"This private prosecution is against an individual breaching rodeo’s own rules. It is not an anti-rodeo prosecution. The investigation showed that the defendant was the only person using an electric shocker at the events. He was asked several times to stop by other rodeo cowboys who saw him shocking the calves unnecessarily. NZALA believes disciplinary action should have been taken by the Rodeo Cowboys Association against the defendant."

The association says one of its purposes in filing the prosecution is to have the defendant banned from participating in further rodeo events.

"It is important that rodeo cowboys maintain a high level of care towards the animals and protect them from unnecessary abuse and ill-treatment."