(CNN) -- Last fall, a mother driving a vehicle with five children inside was pulled over for speeding in New Mexico. The dramatic minutes that followed showing a series of confrontations between the driver and officers were caught on a police dashboard video camera and made national news.
The motorist peels away and is stopped again. One of the officers involved is seen on tape firing at the vehicle when the motorist drives away again. The woman is now facing child abuse charges related to the incident, according to CNN affiliate KRQE. The state police officer who shot at the car resigned.
Dashboard cam videos like this one have often played a role in documenting interactions between law enforcement and citizens. When those interactions go terribly wrong, as was the case in the shooting death of Ferguson, Missouri, teenager Michael Brown, it seems logical to ask: Where is the video?
There is none, Ferguson's police chief said.
Thomas Jackson says his department has 18 patrol cars. This spring, the department purchased two dashboard cameras and two wearable body cameras, but the equipment hasn't been installed because the department doesn't have the money to cover that cost, he said.
A dashcam and installation runs about $3,000, he told CNN.
The August 9 shooting has sparked days of protests and violent confrontations between police and the community. The details of what happened between the officer and Brown wildly differ from witness accounts and police accounts, leaving many to wonder whether a dashboard camera could have shed light on what happened.
Technology that improves policing
Dashcams have been available widely since the 1980s, though the first attempt to put a camera in a police car occurred in the 1960s.
Mothers Against Drunk Driving's 1980s campaign against impaired driving drove home the need to have video documention of traffic stops. In the 1990s, increased crime related to drugs and more allegations of racial profiling prompted departments to install more dashcams.
But it was the 1991 police beating of African-American Rodney King in Los Angeles that spurred a national discussion about how vital a tool video can be in incidents involving authorities, said David Harris, a law professor at the University of Pittsburgh who has studied the use of cameras in policing.
A witness to King's beating shot the footage from his apartment window on his personal video camera. The tape was broadcast repeatedly on national television and played a pivotal role in the criminal trial of the officers involved. Their ultimate acquittal outraged many and sparked the L.A. riots.
The images of Rodney King being pummeled into the pavement also stirred debate -- not just among communities, but within police departments who wanted their own recording of their encounters.
Didn't that make sense in an age where it was becoming commonplace for citizens to videotape?
"Back in the day, police officers were initially resistant to using them," Harris said. "They felt like they were being spied on, or that they weren't trusted to do their job. But after awhile, they realized it was the best possible tool to prevent someone from making a bogus claim against them. They realized that if they were doing their job, footage could back them up."
A 2005 International Association of Chiefs of Police report found that cameras aided law enforcement -- improving officer safety, often backing up the officer's version of events, reducing department liability and conveying to the community a sense of transparency.
Some officers reported that they reviewed footage they recorded in order to critique themselves, the report says, and cameras cut down on the number of complaints a citizen made claiming mistreatment after the citizen was informed that there was footage of an incident.
In interviews and surveys of officers with 21 law enforcement agencies across the United States, the vast majority -- 86% -- said cameras did not affect the officers' discretion in handling situations and 89% said it had no effect on their decision to use force. In other words, when they felt that they needed to use force, the camera didn't make them hesitate.
By 2007, 61% of local police departments were using video cameras in patrol cars, up from 55% that were using them in 2003, said the U.S. Department of Justice, which has provided grants to help law enforcement buy recording equipment.
But dashcams have limitations, Harris said.
Most only capture what's happening in front of the car. Some don't pick up sound, so officers wear microphones that sync with the cameras, Harris said, and all it takes is a popped hood to obscure the view of a dashcam.
A turn toward body cameras
To address these shortfalls, body cameras are gaining popularity among law enforcement worldwide.
Perhaps the strongest argument for more mobile cameras is this: Everyone has a cellphone and citizens are going to shoot video. Shouldn't law enforcement acknowledge that reality and have their own visual account of an incident?
Officers in the United Kingdom were the first to experiment with body cameras, Harris said. They found that the cameras did more than simply record an encounter; they also had an interesting effect on people who were confronted by police.
"Some people who weren't behaving suddenly started behaving knowing that what they were doing was being filmed," Harris said.
Used with apps and other technology, the devices also allowed officers to record and maintain records in real time, which led to faster resolutions of cases.
But sticky questions have been raised.
There are concerns about privacy. Police are called after terrible things happen to people. Could recording expose victims? When do officers begin recording? Only during certain situations or in every situation? Could footage, depending on when the record button is pressed, present a false or misleading account of an encounter?
When does an officer announce that he is recording? Laws governing when and where people can be recorded vary from state to state. Would a person who knows they are being recorded by a police officer be less likely to tell an officer much needed information?
One department's experiment
There are no national guidelines on the use of dashcams or body cameras, said William A. Farrar, the police chief in Rialto, California, a city of about 100,000 in San Bernardino County.
Farrar, a 34-year law enforcement veteran, became intrigued by the use of body cameras in policing while he was on a sabbatical getting his graduate degree at University of Cambridge in England in late 2011.
When he returned full time to the department, he partnered with Barak Ariel, a fellow at the Institute of Criminology at Cambridge, and set out to do a yearlong study. Between February 2012 and February 2013, some of his officers would wear body cameras, purchased with grant funding.
Farrar wrote a policy based on input from his officers and guidance from the Los Angeles branch of the American Civil Liberties Union to assure that guidelines adhered to privacy laws.
"I truly believe that cameras had a positive impact as it relates to increased professionalism -- officers minding their P's and Q's -- and being more sympathetic to what was happening in the community," he said. "At the same time, the cameras also got citizens who interacted with officers to calm down. It mitigated a lot of circumstances instead of escalating them."
Use of force by Rialto police dropped 60% during the experiment year, Farrar said.
The long-term benefits of having cameras far outweighs the financial costs, Farrar said.
One of the best examples of that came the first week that the officers had body cameras. A call came into Rialto dispatch from a person describing a man who was in a car with a gun. Officers showed up and discovered a man sitting in his car. The man's voice sounded the same as the man who had placed the call, and records showed that later, Farrar said.
But that day, on the street, the man got out and raised his weapon toward an officer, the chief said. And the officer shot him.
"It was a classic suicide-by-cop," explained Farrar. "He called us because he wanted that confrontation."
If the man holding a weapon toward the officer wasn't caught on body camera, the situation might have been misconstrued because another person -- a witness filming from afar -- also captured the confrontation on video camera and sent it to local press.
On that second video, you can hear a voice saying that it appeared that an officer had, without cause, shot a man in the street.
"We had video that showed what really happened," said Farrar. "It made all the difference."
CNN asked Farrar for his thoughts about Ferguson's lack of police cameras.
He said he didn't want to criticize another police department.
Law enforcement has faced financial hardship in the past several years. "Agencies have downsized and reduced staffing and budgets are tight," he said.
But, Farrar said, "at some point every police chief should really ask themselves ... are we doing everything we can?"
Chief: No video of shooting
Chief Jackson has said there is no video of Michael Brown's shooting.
The two versions of what happened on the afternoon of August 9 come from witnesses and police, and they are vastly different.
Witnesses say that Brown, 18, and 22-year-old friend Dorian Johnson were walking down a street and an officer drove by and shouted for Brown and Johnson to move to a sidewalk. Johnson has said that they told the officer that the friends were close to their destination and would move.
The officer, Johnson said, threw his squad car in reverse and had a confrontation with he and Brown, at one point opening his car door into them. The officer reached out of his squad car and attempted to choke Brown, Johnson said.
Johnson said that neither he nor Brown were armed. At some point the officer got out of the car and shot at them, Johnson said. The officer fired multiple times, he said, eventually killing Brown.
St. Louis County Police, a separate entity from Ferguson police, is conducting an independent investigation.
Earlier this week, St. Louis County Police Chief Jon Belmar said that Brown reached into the officer's car and tried to get the officer's weapon. Brown was shot about 35 feet from the police vehicle, according to Belmar, who declined to give more details.
Two witnesses CNN interviewed Wednesday said Brown did not try to get the officer's weapon.
"It looked as if Michael was pushing off and the cop was trying to pull him in," said Tiffany Mitchell.
Piaget Crenshaw said that she shot cell phone video of the aftermath of the shooting. She said the officer and the teen appeared to be arm wrestling when a shot went off. The teen broke free, and the officer got out of his car to run after him. "I saw the police chase him ... down the street and shoot him down," Crenshaw said.
No expectation of transparency
The FBI also has opened an inquiry into the shooting.
"Only when the FBI takes control of this investigation will there be any kind of transparency or hope for justice," said Antonio French, an alderman in St. Louis, on Wednesday to CNN. "No one in the community has any expectation that there will be a clear truth of what happened. Could a camera have helped? I don't know. It might have been a start."
Sixty-seven percent of Ferguson's residents are black. Of the police department's 53 officers, three are black.
"This is about not understanding or relating or being empathetic to the community the Ferguson police department are supposed to serve," French said.
Witness Dorian Johnson told CNN the officer was white. Ferguson police initially said it would release the name of the officer but backed away from that this week. Chief Jackson said that threats had been made on social media against another officer who was incorrectly identified as the shooter.
Ferguson has been akin to a "war zone" this week, said Gov. Jay Nixon.
A vigil for Brown and non-violent protests against police disintegrated into violence and looting Sunday night. One officer was caught on camera calling protesters "animals." There were marches through the town during the day, with people shouting, "No justice...no peace!" but by nightfall, violence erupted again.
On Wednesday night, officers were firing tear gas and rubber bullets into crowds. Much of the chaos has been filmed as a national news spotlight is firmly trained on Ferguson.
The night that French spoke to CNN he was arrested. He said police came through a part of Ferguson and began trying to disperse a crowd with smoke bombs. When that didn't work, police warned the crowd and then released tear gas, he told CNN.
French said that didn't work to break up the gathering, so he went to his car to try to drive away.
Police approached his vehicle and pulled him from his car and handcuffed him with zip ties, he said.
It's unclear whether anyone got that on video.
CNN's Tristan Smith contributed to this story.