A loophole in the law allowed an Auckland police officer to avoid a drink-driving blood test.
The suspected drink-driving by Constable Matt Hooper happened two days before former police national prosecutions manager Superintendent Graham Thomas refused a breath test in Wellington.
Mr Hooper, a former team policing officer, refused a breath test when pulled over in the city about 11pm on December 11 last year, the New Zealand Herald reported.
Officers took him back to the police station where they intended to obtain a blood sample.
It was understood he was allowed to go to the toilet, but emerged with a head injury and had to be taken to hospital.
A Land Transport Act technicality states that blood collected in a hospital for testing the presence of alcohol can be used in a court only if the suspect has been hospitalised because of a car accident.
Police spokeswoman Noreen Hegarty said Auckland City police carried out a criminal investigation into the suspected drink-driving but, because of the technicality, there could be no criminal charges laid.
Mr Hooper was currently the subject of an ongoing employment practices and code of conduct internal investigation, she said.
In the case of Mr Thomas, witnesses reported seeing him driving erratically through Wellington but when police officers knocked on his front door and asked him to take a breath test he refused.
He had a legal right to refuse, but Police Commissioner Howard Broad said later Mr Thomas had a moral duty to take the test.
He said there were "unique circumstances" in the case which made full disclosure of the details difficult.
Mr Thomas was cleared by an internal investigation and is now on paid sick leave.
