The unblinking eye of a dashboard camera in a police car can be a career-ender.
That may be the outcome for Officer Robert Powell. His dash cam preserved his 13-minute harangue of Ryan Moats during a traffic stop earlier this month as the young NFL player pleaded with the officer to let him be with his mother-in-law dying in a nearby hospital room.
The video, released last week, went viral and has sparked nationwide outrage. Police Chief David Kunkle has been inundated with calls to fire Powell, currently on leave. On Friday, Powell called the incident "unfortunate" in a statement released by his lawyer.
As bad as Powell's experience has been, experts say that for most police officers, in-car video can rescue a career threatened by a bogus allegation of misconduct.
The power of video was cemented 18 year ago by the infamous Rodney King beating by Los Angeles police officers.
Cameras, both in-car and wielded by bystanders, have "had a huge impact in being able to provide independent visual documentation of the incident," said Sam Walker, a national police accountability expert.
"If the officer did the right thing, then it's good for us to know that and have some independent documentation," he said. "If the officer was in the wrong, then it's good for us to know that. This is what's been lacking in most police use-of-force incidents. Traditionally, you would have had a he said-he said situation. As the clich has always been, the tie goes to the officer."
In the Powell-Moats incident, without the video or if a Plano officer hadn't witnessed part of the traffic stop, an Internal Affairs inquiry might have gone nowhere. The Plano officer reported the incident to his supervisors.
"It would have been their word against [Powell], and it probably would have ended up being inconclusive," said Assistant Chief Floyd Simpson, who oversees the city's seven patrol stations. "The in-car camera systems bring a different view."
About 67 percent of Dallas' 906 squad cars are outfitted with cameras, which cost about $4,400 each, said Lt. Dale Barnard, the department's fleet coordinator.
The digital camera begins recording automatically when an officer flips on lights and sirens, or if the patrol car is in a crash. Officers are required to wear microphones to record conversations. It is a violation of DPD rules for an officer to turn off the camera, and officers cannot erase the videos.
Officers download the videos, but a sergeant preserves those that need to be kept longer than 90 days or those to be used as evidence.
Figures from the federal Bureau of Justice Statistics show that in 2003, 54 percent of police departments in cities with more than 250,000 people were using in-car cameras. That's up from 34 percent in 2000.
Last year, dash-cam video was a mixed bag for Dallas police officers.
Some officers found themselves cleared of misconduct allegations. Others had wrongdoing exposed on video. Other instances led to tweaks in department policy.
In August, two Dallas police officers arrested a drunken man at a club near the southwest patrol substation. The man later complained that the officers had roughed him up. But the officers were exonerated after investigators heard an audio recording showing that the man was yelling, screaming and kicking the cage in the squad car.
On Sept. 16, a furor erupted when a Dallas officer shot and killed an unarmed hit-and-run suspect, Derrick Jones. The uproar all but evaporated when police brass released the dash-cam video. It showed a 6-foot-3, 240-pound Jones pounding the smaller officer in the head just before the fatal shot.
Dash-cam video resulted in several reprimands after a Sept. 6 chase.
Police launched an internal investigation after video showed an officer racing more than 20 miles across Dallas to join the chase. The video showed him careening in and out of traffic at 100 mph before he crashed and was injured. After pulling all the in-car videos, supervisors ended up disciplining 21 officers, including the injured one, for violating department policy.
A Dallas police dash-cam video also showed the Oct. 17 death of 10-year-old Cole Berardi, who was struck by an officer driving at least 29 mph over the speed limit on a darkened road. His sirens and emergency lights were not on.
That video helped persuade Kunkle to issue new driving guidelines, requiring that officers not drive above the speed limit unless lights and sirens are activated.
Recent police videos have sparked outrage elsewhere.
On New Year's Day, bystanders armed with cellphone cameras in Oakland, Calif., captured a 27-year-old transit police officer shooting Oscar Grant, 22, who was being detained along with several other young black men while police investigated a fight on a train.
Grant was lying face down when the officer pulled the trigger, and bystanders are heard gasping, then screaming at the ring of officers surrounding Grant's body. The officer is facing murder charges.
In Maryland, a dash-cam video that surfaced this month resulted in prosecutors in Prince George's County dropping charges against a 30-year-old motorist accused of assaulting two cops. The video showed the officers using batons and pepper spray on the unarmed man, who had refused to sign a traffic ticket.
But for the vast majority of officers, dash cams are reputation-savers in alleged misconduct cases, said Mike Fergus, a program manager for the International Association of Chiefs of Police who studied how nearly two dozen state police agencies used dash cams.
"Our study found that, if there's a complaint filed against an officer, and if the incident was recorded, 93 percent of the time, an officer was exonerated," Fergus said. "Mostly, it's someone saying the officer was rude, and the sergeant says, 'Let me pull the video,' and then click. It's dropped."
Dallas police Senior Cpl. Herb Ebsen, 54, is a supporter of having cameras in the cars, but he said some of his colleagues do see drawbacks.
He said officers fear that comments made inside the privacy of the squad car may be used against them. Also, the angle of the camera may not capture the full context of an incident.
"It doesn't always put everything in context and in complete reality," said Ebsen, a 26-year veteran. "They can save you or they can kill you. Without a doubt, we know they can all be used against us. Officers feel it's kind of a Big Brother issue."
That's a common sentiment among officers across the U.S., said Nathan Triche, who studied hours of in-car video as part of a master's thesis in sociology and criminology at the University of North Carolina at Greensboro.
"No one likes being closely supervised," said Triche, a five-year veteran deputy with the Guilford County sheriff's department in North Carolina. "You wouldn't want a camera set up on the side of your office, monitoring how you speak to people on the phone. You're going to end up with people feeling like they're micromanaged."
When questioned by commanders facing increasing public outrage, Powell, who has been a Dallas officer for three years, told his superiors he felt he did nothing wrong in the Moats traffic stop.
According to several Dallas police officers, many young officers share Powell's assessment of the incident. Seasoned officers who have seen the video, including most members of the command staff, said they were aghast and embarrassed at Powell's conduct.
Simpson, the Dallas patrol assistant chief, said in-car cameras haven't "changed police work in my mind. We still do pretty much what police officers do. But it has brought some things to light."