The arrest unfolded in real time, behind a bank of television microphones at Perth’s busy Mirrabooka bus station. As Western Australia’s police commissioner, Col Blanch, spoke to reporters on Thursday 2 July, a camera mounted on a nearby marked police van had been quietly panning across the interchange. It can scan hundreds of faces a minute, instantly cross-referencing their profiles against a database of about 4,000 people: those with outstanding arrest warrants, registered child sexual abuse offenders and people reported missing. Midway through the media conference, the algorithm pinged. Officers stepped into the crowd and led away a woman wanted for failing to appear in court. “Commissioner, can we just get your reaction? There’s just been an arrest from the cameras behind you right now,” a reporter said. “Been happening all week,” Blanch said. “I’d love to say I planned that but I think that’s exactly what the technology is … People are being arrested because they are wanted.” The striking live demonstration marked the public debut of an Australian-first for law enforcement: a five-month mobile trial of real-time facial recognition technology. While Australian police have used facial recognition retrospectively on stored footage for more than a decade, this trial uses live video feeds for real-time alerts. In its first week, the single police van scanned more than 130,000 faces in crowded public spaces, generating 33 alerts that resulted in 19 arrests. The technology also prompted two welfare checks and identified 21 registered sex offenders who were “engaged with” by officers. While WA police and the state government hail the trial as a cutting-edge tool for public safety, it has come under criticism from experts and regulators. The state’s independent privacy watchdog, the Office of the Information Commissioner WA (OIC WA), said it was not involved in implementing the trial,