Kearns admitted he'd had ''15 or 16 beers'' at a mate's place and was driving home.
A blood sample later showed 236mcg of alcohol per 100ml of blood, nearly five times the legal limit.
Kearns had previous convictions from 1992, 1993 (twice), 1996, 2008 and 2013, but defence counsel Pete Tuala said his client had not consumed alcohol for the past four months.
The incident in September, the lawyer said, had been caused by him becoming ''overwhelmed'' by the issues in his life.
Kearns was banned from driving for 28 days, with the alcohol-interlock licence to follow, and ordered to pay $302 analyst's fees.
Meanwhile, the Dunedin court this week also heard a text-book example of how to be caught drink-driving, at the sentencing of Che Akuhata James Cooper, 35.
He was seen by police driving in Hillside Rd on November 2 but did not raise suspicions until making a calamitous decision.
Cooper flung an empty beer can out of his window.
When spoken to by officers, he said he was driving a drunk mate home.
Defence counsel Rhona Daysh said it was a classic case of a man underestimating how intoxicated he was.