But Rialto's randomised controlled study has seized attention because it offers scientific – and encouraging – findings: after cameras were introduced in February 2012, public complaints against officers plunged 88% compared with the previous 12 months. Officers' use of force fell by 60%.
"When you know you're being watched you behave a little better. That's just human nature," said Farrar. "As an officer you act a bit more professional, follow the rules a bit better."
Video clips provided by the department showed dramatic chases on foot – you can hear the officer panting – and by car that ended with arrests, and without injury. Complaints often stemmed not from operational issues but "officers' mouths", said the chief. "With a camera they are more conscious of how they speak and how they treat people."
In other words, they're a useful way of keeping our police in check. The sooner we roll them out, the better.
One question I've seen raised is "who would have access to the footage?" The answer is "everyone" - because it will be official information subject to the OIA. While there are privacy concerns, the Ombudsman's ruling in a case about taser-cams is informative: suspects and anyone featured heavily in the footage will need to give consent for release, while bystanders should be pixelated. As for police officers, there is a strong presumption against them having privacy rights when exercising their official functions.