A police manual warns officers not to use data from new vehicle identification cameras to try to hook up socially with strangers or spy on people for financial or political gain.
A police trial of the automatic number plate recognition cameras is due to end and will be evaluated to see if it is worth expanding.
However, this week the cameras were listed as one of the ways to achieve the Government's goal of reducing the crime rate by 15 per cent over five years, indicating there is a will to increase their use.
The Privacy Commissioner has not been consulted about the use of the cameras, and warned such technology had to be used "carefully".
The camera automatically scans licence plates of every vehicle within range and can take up to 3000 plates an hour - or 572,000 a year.
The primary use is to instantly identify "vehicles of interest" - such as cars registered to people wanted for arrest or disqualified drivers.
However they can also be used in covert operations and in stakeouts. All information is kept on a database for six months and can be used to help track people's movements later, such as to check an alibi.
A police spokesman said the force did not intend to consult the Privacy Commission because it had its own legal experts to ensure the manual was consistent with privacy law and other legal requirements.
The draft manual for covering the cameras lists examples of improper use, including tracking people where there was no suspected unlawful activity. It gave the example of an officer seeing someone they want to meet socially and noting their licence plate so they can check the database for that person's movements and then try and bump into them.
Other examples of improper use were recording registration numbers of people attending peaceful protests so police could check the attendees later, or using it for political, financial or commercial gain.
A police spokesman said advice about not using data for personal or social reasons was consistent with general instructions to all police staff.