The Police Commissioner says expectations around drink-driving weren't as high when he was convicted 34 years ago, but they are rightfully higher now.
Mike Bush revealed today he was caught in Auckland in 1983, when he was a 23-year-old detective constable. He was off duty at the time.
He pleaded guilty, was fined $250 and disqualified from driving for six months.
Mr Bush told Checkpoint with John Campbell today that he was fractionally over the limit, but his conviction would have barred him from the police force if he had been caught after 1991.
"I knew I'd done wrong, but the more I reflect, the thing that concerns me is that I did something dangerous. It wasn't a good thing then, it was wrong, and it's wrong now. And I congratulate police and all of the partners who work in this space to have moved that culture."
He said the matter was disclosed during his appointment to the commissioner's role.
"Back in 1983, expectations were different. Obviously I reported this to my supervisors straight away. The matter was acknowledged and dealt with, and I've been reflecting on it ever since. but it did not impact on my career."
In a blog published today, he apologised for his "extremely poor judgement".
"It was extremely poor judgement by me 34 years ago, for which I am sorry," he said in his blog.
"I make no excuses. It is something I deeply regret and have reflected on ever since."