Prof Paul Roth yesterday said nothing in the proposed rule to make cameras compulsory in taxis prevented police using their images in non-taxi related investigations.
If police believed an offender used a taxi, they could use the data to help develop their case, Prof Roth said.
They might also publish the image to help their investigation, so video of someone suspected of committing a crime elsewhere could be run in the media.
"The police will still operate within the usual rules of investigation," he said.
"But broadly, the purpose of the rule is to tackle crime, so using data from the cameras for investigations into events outside a taxi would be fine."
Public consultation on the rule closes tomorrow.
The rule was introduced as a way to combat increasing rates of serious crime committed against taxi drivers.
There were 677 assaults against taxi drivers in the decade to February.
Since 2008, two drivers have been killed on the job.
The cameras will be compulsory in 19 major urban areas including Dunedin, Queenstown, and Invercargill.
Prof Roth said the draft rule did not give taxi companies open access to the data the cameras will collect.
They would only access the data to delete it, or to meet a request for personal information under the Privacy Act.
Data had to be deleted no more than 14 days after the image was captured, unless a complaint was likely, there was a Privacy Act information request, or the police needed it.
The Taxi Federation has signalled it wants designated taxi company staff to have access to the images recorded from inside their company's cars.
Assistant Privacy Commissioner Katrine Evans said companies would have to ensure their customers knew they were being filmed for security purposes.
The Privacy Commissioner supported the idea of limited access to the information.
The rule is expected to come into force February 1 next year.
Taxis already operating will have until August 1 to install cameras.
