Denver police testing use of body cameras as part of study by Taser, University of Cambridge

Some Denver police officers are using body cameras on patrol as part of a study of their effectiveness, and officials hope to have all 800 patrol officers outfitted with the devices by next year.

Officers assigned to the city's busy downtown area began wearing the cameras in June for the six-month study by Taser International Inc. and the University of Cambridge.

The fatal police shooting of an unarmed 18-year-old in Ferguson, Missouri, has prompted calls for more officers to wear simple, lapel-mounted gadgets that capture video of law enforcement's interactions with the public. Proponents say the devices add a new level of accountability to police work.

"Citizens should have a right to know what the officers are doing, and why they are doing it," Denver Police Chief Robert White said Wednesday at a news conference where he displayed the cameras, which can also be clipped onto an officer's eyeglasses. The onus is on the officer to turn the device off and on, but a buffer catches the 30 seconds before the officer started recording to show how a situation escalated.

Without providing specifics, White said the cameras have already helped reconcile discrepancies between officer and witness accounts.

White said Denver is the first city of its size to be part of the six-month Cambridge study. A similar yearlong trial of the cameras in Rialto, California, a city of about 100,000 residents near Los Angeles, showed they reduced the number of complaints against officers and the number of times officers used force.

White said officers will be required to record "pretty much any time they are in an official capacity," such as responding to 911 calls and traffic stops. But the department's still-evolving policy on the cameras will likely forbid their use in more sensitive settings, such as at hospitals, he said.