In October Johnetta (“Netta”) Elzie used her cell phone to help win an ACLU case against law enforcement in Ferguson, Mo. Elzie, a Ferguson activist and co-editor of the newsletter Words Into Action, testified against the so-called “five-second rule.” Police claimed the rule, which restricted the length of time protestors can gather, was congruent with the First Amendment right to assembly.

Police were supposed to set up specific protest areas. Elzie, though, had recorded encounters with police on her cell phone in which they told her that there was nowhere to legally assemble.

“The videos I captured with my cell phone proved that the police were lying and were giving people misinformation,” Elzie told me.

The highest profile videos from the #blacklivesmatter movement are those that show police actually shooting and killing black people. Feldin Santana’s cell phone video (below) of Michael Slager shooting Walter Scott after a traffic stop in South Carolina, and Ramsey Orta’s video of Eric Garner being choked to death by New York police officer Daniel Pantaleo have both served as national wake-up calls and rallying points for protest.

Elzie’s Instagram video of police lying hasn’t had that kind of national profile. But just for that reason, Elzie’s case demonstrate how important cell phones are now in holding law enforcement accountable, not just for the most spectacular cases of violence but for the everyday, petty, drumbeat of abuse.

Cell phone technology makes every citizen a journalist, with the tools to gather evidence either, as Elzie did, for the courts or for the public. And that access can be leveraged in a variety of ways. Netta’s co-editor and fellow activist DeRay Mckesson told me in an interview for the *Atlantic* about how an aggressive officer in Ferguson would cover his badge to prevent protestors from seeing his name.

“So I took a picture of him,” Mckesson said, “put it online, and within 30 minutes they knew everything about him. And that’s a different way of empowering people.”

In addition to helping citizens hold police legally accountable, of course, cell phones have given black Americans an unprecedented ability to raise awareness of the extent of oppression and violence they face from law enforcement.

Joshua Crutchfield, a graduate student in history at Middle Tennessee State University and a member of the Nashville Black Lives Matter Chapter told me that cell phones “have functioned as eyes and ears on the ground via live streams, Vines, and photos when actions and protest are taking place. With camera phones, Americans who might not otherwise have believed the depth of police brutality can now see it with their eyes.”

Or, as Elzie puts it, “I think that a lot of people live in a fairytale where the police can do no wrong, and if you are willingly blinding yourself to what’s happening, seeing a video or a photo of the police beating or killing someone, that proves that everything you believed to be true is actually false.”

The power of that can be enormous, as the reaction to the video of Slager shooting Walter Scott demonstrated. The images of Slager killing in cold blood and then apparently planting a weapon on him effectively undermined all public support for the officer.

Police apparently planting a Taser on Walter Scott, Via YouTube

Police apparently planting a Taser on Walter Scott, Via YouTube

George Zimmerman, who shot Trayvon Martin, and Darren Wilson, who shot Michael Brown, both became folk heroes to elements on the right. Wilson raised nearly half a million dollars online. Slager’s online funding campaigns, on the other hand, were deleted by sites such as GoFundMe and IndieGoGo. Police officials denounced his actions; even his defense attorney resigned from his case. A cell phone camera showed people the truth and seems to have ensured justice.

Given the power of cell phone images, it can be easy to praise the cameras themselves and to see the technology as fundamentally altering the relationship between the state and those subject to the state. But, as Crutchfield says, “We know the limits of cell phones to hold police accountable well. Eric Garner’s death was recorded for the world to see, and yet his police murderers still were not even indicted. So cell phone footage does not equal conviction or even indictment.”

In fact, it’s not the cops who killed Eric Garner who went to jail but the person who took the cell phone footage, for what his family said are bogus charges.

Cell phones alone aren’t going to transform the legal system. But they offer possibilities for transformation that might not otherwise be available. Technology doesn’t cause change itself, but protestors, and those working for change, take advantage of whatever technology they can.

“Much like the mimeograph was utilized during the civil rights movement to disseminate information,” Crutchfield says, “people in this movement, and black folks in particular, have used the tools that are available to them like camera phones and social media to resist and to get out information.”

That’s been the case going back well before the 1960s. In The Half Has Never Been Told, Edward Baptist argues that ideological opposition to slavery began with the slaves, who, among themselves, analyzed and criticized the giant, brutal prison camp that was the Southern United States. Getting that analysis into mainstream white American society was a long, slow, brutal process. And yet the slaves, connected to networks of free blacks, managed it.

Baptist points, for example, to William Watkins and Jacob Greener, African-American men who helped convince abolitionist journalist William Lloyd Garrison of “the radical doctrine of immediate, unconditional emancipation.”

Cell phones are a more immediate way to picture injustice than Garrison’s Liberator, or even Frederick Douglass’ narrative. Phones are valuable in part, too, because they make clear, not just abuse, but those who are revealing the abuse. Elzie doesn’t need William Lloyd Garrison to share her insights via social media, as Watkins and Greener needed him to share theirs via the printing press.

But despite all the technological change, the basic work of holding American law enforcement agencies accountable for their brutality hasn’t changed that much in the last couple of hundred years. Black people, and others facing police abuse, have to create a context, and a framework, in which that abuse is visible.

The incessant message, from politicians, from media, from film and television, is that police are good, and that the people policed are bad and undeserving of sympathy or freedom.

Cell phones can provide images of black people being lied to, beaten or killed. But if black lives don’t matter, those images won’t matter, either. Video is a powerful tool, and if it changes hearts, or institutions, it’s only because black people themselves first created a vision of justice.