Body cameras have not stopped police brutality.

Why is that Lawmakers are once again using the devices as a tool for reform amid worldwide protests against racism and police violence.

In the wake of the killing of MICHAEL BROWN by a police officer in Ferguson, Missouri, which sparked a national "Black Lives Matter" movement, everyone from President Barack Obama to the BROWN family has embraced a relatively new approach: equip police officers with body cameras. If the police knew that their every move was being recorded, they reasoned, they would be more likely to maintain their best behavior. Otherwise, the cameras will at least catch any wrongdoing, making law enforcement more transparent and accountable.

Six years later, nearly every major POLICE department in the United States has used body cameras, but they have failed to prevent more police violence. Technology didn't stop George Freud from being killed while he was in police custody last month. The next day, the Minneapolis police department said the body camera was "on and on" and charged Floyd with resisting arrest. But video from bystanders and security cameras, not body cameras, revealed something law enforcement didn't mention: Mr. Freud died after a police officer, Derek Chauvin, placed his knee around his neck and held him to the ground for nearly nine minutes. Floyd's death was later ruled as homicide and four officers are now facing criminal charges, including second-degree murder of Chauvin.

Body cameras have long attracted policymakers as tools for police reform. Now, in protests around the world against racism and police violence, government officials are using the devices again. On Wednesday, Senate Republicans unveiled a police reform bill that would encourage wider use of body cameras. In Canada, the head of the Royal Canadian Mounted Police announced this month that she would seek to equip her officers with the weapons to increase public trust.

"People see body cameras as a silver bullet," said Harlan Yu, executive director of Upturn, a nonprofit that works on advancing technology policy. By themselves, however, these devices do not create more accountability and transparency. What matters is how the police use them. Mr Obama recognised the same thing five years ago. "It's not a panacea," the former President said in 2015. "It must be integrated into a broader cultural change and legal framework to ensure that people's privacy is respected."

Policymakers need to strike a balance between privacy and the public's ability to access body-camera footage. Although there are some state laws governing what to do with the data, in many places the policy on body cameras is left to the police. Upturn and the 2016 scorecard created by the Conference of Civil and Human Rights Leaders found that policies from 50 major police departments varied widely. Some cities do not explicitly prohibit officials from tampering with videos or allowing people who have made allegations of wrongdoing to watch videos of their cases. "Even if you are the object of the lens in many places, you don't have special access rights," Yu said.

In New York City, the Civil Complaints Review Board, which has the power to investigate allegations of police abuse, said last year that it had not received video requests in hundreds of cases. The CCRB points out that sometimes the NYPD denies that tapes have always existed. "In one case, the NYPD told the CCRB three times that there was no video of any incident, which was later leaked to the Daily News," the agency said in a memo.

Even in high-profile incidents, such as when a person is killed while in police custody, body-camera footage is usually not released to the public. Upturn analyzed 100 fatal police shootings documented by the Washington Post since 2017 and found only 40 that were believed to have been videotaped. In many cases, material can only be released under significant public pressure or court orders. In Texas, the Dallas Morning News spent three years trying to obtain videotapes from the killing of Tony Timpa. Tony Timpa died in police custody in 2016. "We see a lot of cases where it can take months or even years to share violence and wrongdoing when police show footage of bodies to police departments." Albert Fox Cahn, executive director of the Surveillance Technology Oversight Program at the nonprofit Urban Justice Center.

Protests since George Floyd's death have prompted some police departments, including those in New York City and Dallas, to enact new, more transparent body-camera policies. As far as Floyd is concerned, most of the available videotapes have yet to be released, with the exception of those from the nearby Minneapolis park police. A spokesman for the department told NBC News in late May that "human body photography is not public data."

Ultimately, the ability to hold police departments accountable to body cameras often depends on the rules set by those departments. It is often easier for the public to obtain evidence from external sources, such as witness cell phones and CCTV cameras, than from body-camera footage. As in Floyd's case, these videos are often used to hold police officers accountable for ACTS of violence. "A body video of a police officer is completely different from a video of a bystander," Strauss-kahn said. "Who controls the lens and where it is stored has enormous power."

This does not mean that body cameras will never help police hold accountable, especially when the footage is quickly released. Three years ago in Baltimore, one of the devices caught a police officer planting drugs at a crime scene. He was later convicted of fabricating evidence. After Rayshard Brooks was fatally shot by a police officer in Atlanta on Friday, footage of the body was quickly released and the officer was fired. But in general, advocates like Yu say, the body camera has not lived up to the lofty expectations many had for it after Michael Brown's death. "Body-worn cameras are simply not in the interest of most local communities and should be seen first and foremost as tools of policing and surveillance," he said.

Research on the impact of wearable cameras on policing has been mixed. Some studies have found that officers wearing police officers are less likely to use force and less likely to cause civilian complaints. But a 2017 randomized controlled trial in Washington, D.C., involving more than 2,000 police officers, found that the effect of human cams was too small to be statistically significant: officers wearing cameras used force and received complaints at the same rate as their colleagues who did not. An analysis of 10 previous studies of body cameras in 2016 also found that they had "no significant effect" on the use of force and actually increased the likelihood that an officer would be beaten.

This is reflected in the experience of some law enforcement officials themselves. "You forget about the camera very quickly," said Betsy Smith, a retired police chief with nearly 30 years of experience. "It doesn't change our behavior because most police officers just go there to do their job. If people think, let's get these police officers' body cameras to change their behavior, I think it's really naive and frankly, it's an affront to law enforcement." But Smith is not opposed to body cameras. She said she was in favor of having one officer for every police officer in the country, but not necessarily because filming them would hold them accountable.

By design, body-worn cameras point outwards towards the world, usually helping the police to spy on the community rather than the community to spy on the police. And surveillance technology is only getting more sophisticated: OneZero reported earlier this year that at least one body CAM maker has added real-time facial recognition to police departments.

Rather than changing police behavior, Mr. Smith said, body cameras often help exonerate officers who have been improperly charged. The video could also be used to assist police in the preparation of incident reports, although Yu noted that this ability could give police an advantage over other witnesses who rely on memory alone. Despite its advantages, Smith acknowledges that body cameras could bring more work to police departments. They have been plagued by cyber security issues; Some of the equipment even caught fire. Then there is bureaucracy. "You have to control the lens, you have to document it as evidence, you have to store it and maintain it, and that's really expensive and complicated," Mr. Smith said. "This is not an iPhone on your chest."

The ongoing "Black Lives Matter" protests have reignited broader thinking about how American cities, and black communities in particular, are regulated. In a recent survey, a majority of Americans said they believed Freud's death was a symptom of a larger problem and that law enforcement needed to change. While Senate Republicans have proposed reforms to expand the use of body cameras, others question whether the technology is really worth it, especially if the cameras don't stop cruelty. "When we cut funding for schools, when we cut funding for public health in the form of a pandemic, the idea of spending millions of dollars to preserve body cameras that are often hidden from the public seems like a real waste. For me, "Kahn said.