Over the last several weeks, social media has been filled with videos of police officers pepper-spraying, bludgeoning, and shooting protestors. They were captured by civilians, recording on smartphones — not by police body cameras. That changes how people understand the events on the video, helping protestors rather than police shape the narrative.

Many people treat video footage, regardless of where it comes from, as objective evidence, says Mary Fan, a professor at the University of Washington School of Law who studies cameras and police encounters. “The temptation is to see it as a window into what really happened,” she says. But that’s not the case: the place the video comes from has a big impact on how people interpret it. 

“Police body cameras and bystander cameras can tell different stories because they’re often at different angles, and they are focusing on different aspects of the encounter, and may turn on at different times and capture very different stories,” she says. 

Unlike body camera footage, which only shows the officer’s point of view, videos from civilians can capture a full scene or even take the perspective of a suspect. “With bystander footage, other people can demonstrate what’s going on, and we’re not relying on officers to show these events,” says Kristyn Jones, who studies how people perceive footage of police encounters at the John Jay College of Criminal Justice.

Body cameras show a scene from the perspective of the officer, and the image on the screen is focused on the suspect. That changes the way the incident is interpreted. People are more likely to think an object or person in their field of vision caused something to happen. A surveillance video, on the other hand, puts the officer’s entire body on-screen along with the suspect, eliminating that psychological effect.

The perspective changes have real consequences. Let’s say an officer shoots a suspect and there are two videos of the incident: a body cam video and surveillance footage. People are more likely to think the officer was justified when they view the body cam video and less likely to think so when they view the surveillance footage, according to Jones’ research.

“You can see both people more equally, and that helps get a better perspective on what’s happening,” Jones says. 

Body camera footage is particularly biased when it captures an officer physically engaging with someone. “Certain uses of force are really difficult to see when it’s just the body camera,” she says. “With close up contact, people have much different interpretations when it’s a body camera versus bystander footage, or footage that shows both actors equally.” 

Some incidents recorded at protests, for example, showed police officers striking protesters with batons. Body cam footage mostly doesn’t capture how the officer winds up before striking — making it harder to tell how much force went into the strike.

Relying on police officers for the documentation of an encounter also puts them in control of the recording. Police often don’t turn their body cams on — even when they’re supposed to. Even if there is footage, it may never be released or it may be edited before the public sees it, Jones says.

Bystander footage can also be selectively edited and may not capture the full context of an encounter. Video is also subject to the same confirmation bias as any other type of information, Fan says. People are more likely to interpret video footage in a way that reaffirms their existing beliefs: someone inclined to distrust the police will think a video shows a cop acting violently, while someone who identifies with law enforcement may think that same video shows that the cop was justified. 

“When a camera gets activated, whether it’s a community member’s camera or an officer’s camera, it can lead to misperceptions,” she says. 

Videos from outside observers, though, can change the power dynamics between civilians and police, Fan says. “We’re never on a totally equally playing field when it comes to whose story gets told, and whose story gets believed,” she says. 

It’s a volatile equalizer. Videos can be painful and inflammatory, and they don’t fix every imbalance, but they can help support someone whose word may otherwise be discounted, she says. “With just body cameras, only one side gets the power over what gets recorded.”