Police officers on a traffic patrol in Takaka, Golden Bay, who drove without headlights on to trap motorists, are facing unspecified disciplinary action.

After an investigation, Nelson Bays area commander Inspector Steve Greally said police were satisfied that an unmarked police vehicle was driven with the headlights switched off on February 18 around the Golden Bay town.

"The matter is now being dealt with as an employment issue with the individuals involved and as such it would be inappropriate to comment further on that process," Greally said.

He said while the police force was a public organisation subject to public scrutiny, it was also an employer.

"As an employer we have obligations to the employees. However, be well assured that it has been dealt with effectively."

Greally concluded his report with a reminder of the policy about driving without headlights on.

"Police advise that driving without lights is not a tactic that police condone or will tolerate and this has been communicated to all staff."

The incident was exposed by Takaka resident Steven Wilkinson in February and was initially denied by Greally.

But after further inquiries, he said officers from the traffic and alcohol group had admitted that on February 18 they had driven around Takaka without their lights on.

The road code is unequivocal in its rules about headlights: "You must turn on your vehicle's headlights from 30 minutes after sunset, until 30 minutes before sunrise."

Failure to do so normally results in a $150 fine and demerits on the offending driver's licence.

Wilkinson said he was pleased the investigation had overturned the initial denial and confirmed his complaint.

But he questioned the "open" style of Greally's statement.

"It's more than an employment issue, it's also dealing with disobeying the law," Wilkinson said.

"Steve Greally is talking about a new style of policing which I am all for. It seems the conclusion of his investigation is still very old-school style where there is no transparency at all or anyone seeming to be penalised for this as well."

Wilkinson said he was also disappointed that the report failed to address the treatment of tourists outside the Roots bar on February 18.

The bar's owner has said he saw a car that had been driving without headlights on pull up sharply outside the bar. Police officers got out of the car and forced a group of tourists to empty their bags and pockets. No charges were laid.

Greally declined to answer questions about that incident.

Despite the lingering questions, Wilkinson was satisfied to get some resolution and hoped that the matter would make police more mindful of following the law.

"I don't think this is an isolated incident," he said. "Since this has happened people have been telling me their personal experiences where they were pulled over by other officers in marked cars travelling with no headlights."

Wilkinson has alerted Greally to these other instances of misconduct.

"It has been an unspoken standard operating procedure," said Wilkinson. "Now that they have been caught out, hopefully this behaviour will stop."