WA Police reveal number plate recognition trial in operation at Westfield Carousel

Cameras that record the number plates of all the vehicles that enter one of Perth's major shopping centres are being used to track criminals, WA police have revealed.

In a deal inked with the owners of shopping giant Westfield, police now have access to the company's number plate recognition cameras at Carousel shopping centre in Cannington, allowing authorities to detect if repeat offenders or wanted individuals enter the precinct.

WA Police Commissioner Col Blanch said the focus was on preventing crime against retail workers.

"Why wait for people to be attacked and call Triple Zero?" he told ABC Radio Perth.

Mr Blanch said the program was in a trial stage, with plans for the technology to be expanded elsewhere if proved successful.

"It does work … particularly with stolen cars when they try to go into a shopping centre or a location where we have these number plate readers," the commissioner said.

He flagged expanding the purpose to control other forms of crime.

"Let's say for example someone who is a serious sex offender and has been released from prison is in the vicinity of a shopping centre," he said.

"I think it's important that we as police know and at least again we can dispatch police to be in the area and patrol with high visibility and be ready to act if necessary."

Mr Blanch said there is already an existing number plate recognition network across the state, including at Perth Airport.

But he said this was the first time WA Police were specifically using the technology in retail areas.

Privacy concerns

Dr Adam Andreotta, an expert in data privacy and AI ethics at Curtin University, said there were some privacy concerns to be aware of.

"If you see a sign that says we might be capturing this information, sure, that counts as a form of consent," he said.

"The really difficult and ethically important thing to receive here is informed consent.

"What is being done with that information? How long is it being held on to?

"If you don't have all of that information, it's pretty hard to see how you can actually give informed consent.

"If you're thinking about a shopping centre, how are you supposed to get consent from individuals if thousands of people are coming?"

Mr Blanch argued there were plenty of existing checks and balances on police activities.

"We have plenty of oversight bodies like the CCC [Crime and Corruption Commission], the Ombudsman, the court themselves, the media, the public opinion on how we do things," he said.

"We've got to be very transparent in how we use people's information."

Mr Blanch said he understood some in the community may be concerned about what police are doing with the data.

He said police keep the number plate data for 12 months before deleting it.

"The most important thing to remember is when your number plate is flagged because it's a stolen car, you're a violent person, you're a recidivist offender, then they're the people that we're targeting," he said.

"We're not interested in people's data that have no interaction with police whatsoever."

Commissioner open to facial surveillance

Commissioner Blanch said police do not use live facial recognition technology, but he is open to trialling it with large retail partners.

"But again, I think the important part … is let's have a public conversation about it," he said.

"I think we've got to work with our community to make sure that they're comfortable with this approach.

"I think we have to document what we're going to do with the images. And I think we have to be quite public about that and say, 'we are trialling it in this location'."

Mr Andreotta said there are benefits to these technologies, but it does not come without risks.

"How is this biometric data stored about, say, vehicle movements? Do they create targets for hackers or misuse? Absolutely they do," he said.

"We've seen in the last few years many data breaches, so if personalised information about your movements are being recorded … how well can consumers or these shoppers trust that the data is going to be kept secure?"

Last year, Australia's Privacy Commissioner found Bunnings, Kmart and The Good Guys breached privacy laws by using facial recognition on customers without their consent. 

"I think we'll see in the next few years pushes from companies that will say [this technology] is going to be a way that we can protect security and there will probably be some sort of effort to try to change the laws under the justification that it will protect people," Mr Andreotta said.

"Once you have the cameras in place, it might be able to expand beyond the original trial.