Police body cameras: Positive change in Rialto, California
The police killings of several unarmed black men - and the decisions not to indict the police officers involved in the incidents - have sparked protests across the United States. Another big protest is set for Saturday in Washington DC. In response to the killings, President Obama has said he wants police to wear personal cameras.
Had cameras been recording the interaction between the teenager Michael Brown and Officer Darren Wilson in Ferguson, Missouri , we might now know whether or not he had his hands up, as protesters say, or was assaulting the officer, as Wilson testified in front of the grand jury.
But given that the encounter in Staten Island between Eric Garner and Officer Daniel Pantaleo was captured on video, and also did not result in any charges filed, some are now questioning the value of body cameras.
In Rialto, California, 60 miles east of Los Angeles, the police force there has been using tiny cameras mounted on officers for nearly four years with great success: complaints from the public are down 88% since the department started filming every arrest and interaction. Police and the people they serve both like the programme.
The BBC's Alistair Leithead travelled to Rialto to see the programme in action.
Filmed by Travis Peterson.