A supermarket has been slapped with one of the heaviest off-licence suspensions after selling beer to a man who was so drunk he could barely stand.

Takapuna Countdown in Auckland will be banned from selling alcohol for seven days from February 10 and the staff member in charge will lose his general manager's certificate for 30 days.

Breaches of this type have previously earned suspensions of up to five days and police involved in the case hoped the recent decision released by the Alcohol Regulatory and Licensing Authority would mark a new hardline stance.

The Sunday Star-Times asked Countdown how much the seven-day loss of licence would cost the business financially but received no response.

An industry source said alcohol typically made up 10 per cent of a supermarket's weekly revenue but the cost could be much greater.

"The biggest problem is so many people come in for booze and when you have to put up a big sign saying ‘we can't sell booze' it's the worst thing in the world in supermarket life," he said.

Alcohol Healthwatch director Rebecca Williams said it would "give Countdown a real whack of a wake-up call. They hold responsibilities just like any licensed operator does and I'm glad police have taken this seriously", she said.

On the evening of August 19, 2012, a member of the public called police after seeing Adam McBride drive his car over a kerb and into a garden beside Takapuna Countdown before finally parking.

When he returned to his car with a dozen beers, the concerned bystander watched McBride clumsily drive over two more kerbs on his way out of the carpark. Police found him 2km down the road trying to pull the keys out of his car's ignition without success - 45 minutes after he'd walked into the supermarket.

When officers breathalysed him, he returned a reading of 1441 micrograms of alcohol per litre of breath - more than three-and-a-half times the legal limit.

Constable Simon Colbert said McBride was so drunk he needed help to get out of his vehicle. "He reeked of alcohol and his eyes were bloodshot. His speech was very slurred and he was unable to form sentences or make sense," Colbert reported.

McBride was eventually convicted of driving with excess breath alcohol at North Shore District Court before police turned their attention to the Countdown supermarket that sold him alcohol despite his obviously drunken state.

At a hearing in Auckland on December 12, the supermarket defended the allegation and said Teawhina Komene, who served McBride, could not have known he was intoxicated. The court was shown CCTV footage, which proved the man was demonstrably drunk, according to the authority's ruling.

"When Mr McBride approached the counter with the alcohol, he was seen to almost stumble. At the counter, he swayed backwards and forwards excessively. When compared with other patrons in the premises, his behaviour was noticeable," Judge John Hole said.

McBride also fumbled his One Card, dropped his change twice and police said the smell of alcohol should have been obvious to staff near him. Judge Hole said it was particularly "disconcerting" to learn from Takapuna Countdown manager Peter Hartley that staff did not receive training in assessing intoxication.

Waitemata police Alcohol Harm Prevention Unit acting sergeant Rachael De'Ath said the penalty handed down by the authority was the harshest she had seen and hoped it would send a message to all off-licences.

There was some concession by the authority that supermarket staff had only a small window to assess customers but De'Ath said it was no excuse for serving someone so obviously drunk.

General manager for operations at Countdown Brett Ashley said staff did their best and regularly turned away drunk people. Training measures would be reviewed as a result of the incident.

Williams hoped the penalties would remind other liquor outlets the onus was not only on bars to assess the state of their patrons.

"[The suspension] doesn't sound like a lot [but] with what normally gets dished out for those kinds of offences, I think it's a strong message."