A three-month Fusion investigation that reviewed hundreds of pages of records from five police departments with body camera programs reveals that the way body cameras are used usually serve police more than citizens charging misconduct. And in the data from two cities provided to Fusion, there was little evidence police body cameras reduced police involved shootings or use of force incidents.

One key problem: officers control the record button. They decide when to turn on and off the cameras and have little to fear when violating department policies about recording, Fusion’s analysis found. In many use of force incidents, camera footage doesn’t exist, is only partially available, or can’t be found. And when body cameras are turned on, the footage usually favors the officer’s account, according to police, law enforcement experts and public defenders we spoke with.

“This is one of our biggest concerns – the promise of this technology as a police oversight mechanism will be undermined if individual officers can manipulate what is taped and what isn’t,” ACLU Senior Policy Analyst, Jay Stanley told Fusion.

“There needs to be very strong policies that make very clear when police officers are expected to be recording and back that up with strict enforcement,” he said.

This has relevance in light of President Obama’s plan, announced last week, to get more body cameras onto the vests of police officers nationwide. Michael Brown’s family has demanded that all police officers wear cameras.

The cameras are marketed to police departments as a way to reduce citizen complaints and litigation against officers. Steve Ward, CEO of body camera manufacturer Vievu, told Fusion, “If police officers wear body cameras, 50 percent of their complaints will go away overnight.” He said the cameras “overwhelmingly” help the officers.

That’s what Fusion found in records obtained from five cities currently using police body cameras: Albuquerque, NM, New Orleans, LA, Salt Lake City, UT, Oakland, CA and Ft. Worth, TX.

In Albuquerque, the number of police-involved shootings has not fallen since the cameras were first introduced in 2010. In fact, there has been an increase in the police involved shootings compared to the six years before the cameras were introduced.

The Albuquerque Police Department’s most recent annual report shows there have been 598 citizens complaints investigated by the department between 2011 and 2014 and in nearly 74 percent of those cases, the police determined the allegations were “unfounded,” “not sustained,” or the officers were exonerated.

Albuquerque Police Department spokesperson Tixie Tanner told Fusion that video evidence played a role in the outcome of these cases.

Albuquerque police department policy states officers should record “all contacts with the public that could result in complaints against the department’s personnel.” But the data obtained by Fusion found that police officers failed to follow the department’s body camera policies 60 times in 2013. So far this year, the department has recorded 28 violations of the policy. The Albuquerque police didn’t say how many of the violations involved officers not recording when required to.

The police body camera wasn’t rolling when 19-year-old Mary Hawkes was shot and killed by an Albuquerque police officer in April. The police officer’s camera was turned off when the officer fired his weapon. Just this week, the officer involved was fired after an internal probe found he turned off his camera at least four times. It’s very rare for officers to be fired for failing to properly use body cameras.

In New Orleans this summer, a police officer had her body camera turned off when she shot a 26-year-old man in the forehead during a traffic stop. The case is still under investigation. The department told Fusion there have been 39 internal affairs investigations involving the use of body cameras this year. So far, 17 of those officers were investigated and sanctioned while four were cleared of any wrongdoing. A report conducted by an independent monitor assigned by the U.S. Department of Justice released in August found cameras, including body cameras and the more prevalent police dashboard cameras, were not used in 60 percent of the use of force incidents reported between January to May 2014.

In an email to Fusion, the New Orleans Police Department said it is working to “build a solid system of accountability,” recently introducing “new activity sheets that officers must fill out in the field to “document that they are wearing a working body-worn camera.”

In Salt Lake City, Utah, there have been nine use of force incidents by police officers so far this year. But only one was recorded on a body camera, despite official department policy that states cameras should be on “at all times” when interacting with the public.

“I can give you a body camera but if you don’t turn it on, what’s the point of having a camera,” said Salt Lake County District Attorney Sam Gil.

“The majority of police officers do their job honorably, but the legitimacy of a process is not measured by the actions of 99 percent of police officers, it is measured by the one or two that need to be held accountable and they aren’t,” he said.

Salt Lake City Police Chief Chris Burbank told Fusion the department did not fully implement the body camera program until September of this year and that might justify the lack of video evidence.

“My policy is when you are wearing cameras, when you are in contact with the public, they have to be on,” he said.

Burbank added there is a “false perception” that body cameras will decrease use of force incidents.

“They don’t prevent police misconduct or use of force, they are just an avenue to document officers encounters with citizens and in most cases capture the good work of police officers,” said Burbank.

In Oakland, CA, which has used body cameras since 2011, body cameras were not on during at least two officer involved shootings. A report from an independent monitor found that between July and September of this year some officers failed to activate cameras at critical times, while others went weeks without recording while waiting for broken cameras to be repaired.

The Ft. Worth, TX Police Department didn’t provide detailed data about violations of body camera policies. According to documents provided to Fusion, the police department found all allegations made against police officers since Jan. 1 of this year – with or without body camera evidence – were either “unfounded” or “did not result in discipline.”

“A lot of people are pinning their hopes on the cameras, but the reality is we have to change the culture of policing,” said Miami-Dade Public Defender Carlos Martinez. “That’s changing peoples’ hearts and that’s very difficult to do.”

Miami-Dade County approved $1 million in spending this year to equip 500 officers with cameras, almost half of the total police force. The department plans to start the program next year.

Events of the last week have shown that even seemingly strong video evidence doesn’t always result in charges against officers. The failure to secure an indictment in the Eric Garner case – despite what many believe is clear, compelling video – resulted in nationwide protests.

“The Eric Garner case really illustrates the limit of body cameras. They might play an important role in federal or civil lawsuits but in terms of imposing criminal charges, the result is the same with or without video,” Florida International University law professor Howard Wasserman told Fusion.

Another case earlier this summer in Salt Lake City, Utah left many wondering if 18-year-old Dillon Taylor had to die when police fatally shot the unarmed mentally ill man outside a 7-11 convenience store.

A graphic 9-minute body camera video helped clear the three police officers involved of any wrongdoing. In the video, Taylor appears to be raising his hands at police orders. He also reportedly said, “No, fool.” After the shooting, the officer who fired is heard saying, “He was reaching.”

Salt Lake County District Attorney Sam Gil, who ruled in favor of the police department in the Taylor’s case, say the body camera video was “very important and relevant” to make that decision.

Since the Michael Brown shooting in August, more than a dozen law enforcement agencies have announced their plans to test and buy the cameras, including large police departments like New York, Chicago, Los Angeles and Miami-Dade County.

One small study often cited to argue for police body cameras looked at the city of Rialto, CA. It was mentioned by President Obama’s Press Secretary Josh Earnest, defending the President’s proposal to provide an additional $75 million to support local body camera purchases after the Garner decision. The report found complaints against police officers fell by 88 percent, and the use of force by officers fell nearly 60 percent after the introduction of body cameras. One of the co-authors, Barak Ariel, said the findings aren’t conclusive and more study is needed. Ariel told The Atlantic “the technology is ‘surely promising, but we don’t know it’s working.’”

Alissa Figueroa contributed to this report.

Editor’s note: This story was updated to include additional description of the Dillon Taylor shooting video.