The police have been publicly rebuked by Police Minister Anne Tolley for their "monumental cock-up" in failing to administer oaths properly for sworn officers.
Parliament passed a new law under urgency last night retrospectively validating the unlawful oaths of 63 police who returned to the force in the past four years.
Without the retrospective law, any actions by those officers - including searches, arrests and prosecutions - would have been open to legal challenge on the grounds that they had not been properly sworn in.
Under changes to the Policing Act in 2008, oaths sworn by returning officers had to be administered by the Commissioner of Police or a person authorised by him instead of by district commanders or inspectors.
Mrs Tolley said she was not going to make any excuses for the police.