“Ma’am, could you back up please? Could you give him some air?”

When I started thinking about this article, my focus was set to be on Oscar Grant, the 22-year-old black Californian who was shot to death — while unarmed, and held face down — by a white transit cop on New Year’s Day, 2009.

The fictionalised story of Grant’s final day was turned into an award-winning film, Fruitvale Station. It’s a powerful work, confidently directed by first-timer Ryan Coogler, and it boasts a moving turn from Michael B. Jordan as the tragic Grant.

Fruitvale Station is notable for opening with real, raw cameraphone footage of the incident, sourced from one of the many bystanders who made use of lightweight, mobile technology to capture this instance of appalling institutional dysfunction. This directorial choice casts a dark shadow over the remainder of the film, and seems to acknowledge the importance of authenticity over fictional reconstruction.

It’s a bold move from a young filmmaker making his “calling card” picture, but it reflects a key truth at the heart of the matter: Oscar’s slaying was one of the first such incidents to genuinely go ‘viral’, and would not have gained the same attention had it not been visually captured and disseminated.

Within hours, footage was uploaded to the internet, and reported by news sites. Many viewers were outraged, and took to the streets to protest both peacefully and violently. At the time, various media outlets referred to the ensuing protests as the ‘YouTube riots’, though ‘cameraphone riots’ would surely have been an equally apposite term.

Grant knew the power of cameraphones, too. One of the most powerful images in the film is of him, backed up against the wall, pointing his own device at a looming cop. Clearly, its presence did not act as a powerful enough deterrent.

As I said, however, I’d only intended for Grant to be the focus of my piece. My plan necessarily changed when I got wind, on Friday July 18, of the death of yet another black man involved in a contretemps with the police. This time, the location was Staten Island, the most southerly of New York’s five boroughs. The victim was 43-year-old Eric Garner, a 350-pound father of six, who’d apparently been stopped by the police on suspicion of illegally selling individual cigarettes, or “loosies”.

Following an extended verbal altercation during which Garner protested his innocence and stressed his wish to be left alone, he was jumped by a number of cops, who wrestled him to the ground. One of the officers placed Garner in a chokehold (a manoeuvre banned by the NYPD since 1993) and Garner, who could be heard to repeatedly say the words “I can’t breathe”, suffered a massive heart attack, and died shortly afterwards: a large, crumpled heap on the pavement. An autopsy turned up “inconclusive” results about the exact cause of Garner’s death, but it’s surely safe to say that, had he not been violently assailed by the police, he’d still be alive today.

The incident, like the death of Oscar Grant, was captured on cameraphone by a bystander, and the footage proved integral to the online reporting by the New York Daily News: the publication who broke the story. These stark images provoked outrage on a large scale. Film director Spike Lee, noting similarities between the police’s manhandling of Garner and a cop’s fatal choking of the character Radio Raheem in his 1989 film Do The Right Thing, spliced the cameraphone footage with scenes from the film. Writing in The New Yorker, Jelani Cobb pithily capsulised the gravity of the situation: “It’s entirely possible for an uninformed viewer to believe that Lee’s scene was inspired by Garner’s death instead of preceding it by a quarter century … but it would be wrong to see this as a testament to how well Lee’s film has held up. Rather, it suggests something more basic: the images remain familiar twenty-five years later because time has passed but in crucial ways our context has scarcely changed at all.”

Cobb, distressingly, is right. Yet one difference he doesn’t mention is the presence of mobile phone technology which, with its democratic accessibility and affordability, is a crucial tool of civic journalism, if — sadly — not a preventative measure. Put simply: if this kind of shit goes down, we’ve all got a much better chance of finding out about it now.

Some hours later, a second video of Garner’s killing emerged, this time uploaded to Facebook by Staten Island local Taisha Allen. Allen had taken up a position directly behind the incident, from inside a shop. In contrast to the version embedded into the NY Daily News’ story (which was edited for content and running time), this unbroken, 7-and-a-half minute smartphone short unfolded with the hallucinatory quality and escalating horror of a nightmare. Unpalatable details accrue by the second: did they really keep the clearly unconscious Garner in handcuffs the whole time? Did that medical technician really do her job that poorly? Did that cop really wave smarmily toward Allen’s camera at the end? It might seem strange to assess this footage as a piece of filmmaking, but why not? It’s captured with a steady hand, it’s well-lit, has a crystalline, megapixel quality, and there are even flashes of ultra-macabre comedy. Consider this brief exchange between an officer, whose panic has seemingly raised the pitch of his voice, and a bone-dry Allen:

Cop: “Ma’am, could you back up please? Could you give him some air? We’re gonna get an ambulance, alright?”

Allen: “You got him on the floor, and you’re talking about ‘back up’? Y’all hear this?”

At the time of writing, Allen’s public video has been shared a remarkable 55,171 times.

After I saw Allen’s video, the floodgates opened, but not with regard to Garner’s case. Footage emerged of a Brooklyn cop literally stomping on the head of a prone, fully restrained citizen: this time, the crime was black-on-black. (Comedian Larry Wilmore opined on John Stewart’s Comedy Central show: “It’s not a white-on-black issue, it’s a cop-on-black issue.”) A family in Petersburg, Virginia, came forward to claim that police barged onto their front porch and tried to stop them from shooting video of arrests happening directly in front of their home. In East New York, a seven-months pregnant, 27-year-old woman released photos, taken from a smartphone video, that she said depicted a cop putting her in a chokehold after officers accused her and her family of illegally grilling on the sidewalk.

None of these developments exist in a vacuum. The capture of moving images has always been integral to struggles for justice in American society, particularly with regard to institutional abuse of the African-American community. Consider the actions of Eugene ‘Bull’ Connor, police commissioner of Birmingham, Alabama, during the Southern Christian Leadership Conference’s campaign of 1963. He turned fire hoses and attack dogs against peaceful demonstrators, including children, but didn’t bank on being filmed by news crews. His actions, broadcast around the world, transformed him into an international totem of virulent institutional racism, and contributed to the passage by US Congress of the landmark Civil Rights Act of 1964. Elsewhere, it was for good reason that the late, legendary civil rights-era photographer (and director of Shaft), Gordon Parks, named his autobiography ‘A Choice of Weapons’.

Yet communities no longer have to rely on lone figures like Parks, or — as Taisha Allen’s video proves — worry about the process by which material is selected, edited, contextualised or politicised for televisual broadcast.

Of course, as proven by the complicated fallout from the Eric Garner case, or the deeply disturbing outcome of the Grant incident, simply capturing and disseminating images of police brutality on cameraphone doesn’t equate to a panacea, or guarantee a satisfactory legal outcome. But it can significantly raise consciousness of gravely important issues, and prompt discernible changes in attitude from the establishment. After all, what kind of government would want the world to witness such heinous behaviour from its own police force?

The mistreatment of Garner was so unambiguous, and captured so clearly, that it surely influenced a subsequent police review panel which recommended disciplinary charges against three cops in Staten Island — all assigned to the precinct associated with the Garner case — for using excessive force, then failing to procure medical treatment for a 52-year-old man who died in custody. With regard to cops’ rights to seize smartphones, the Supreme Court seems to be on the side of the citizen: it recently ruled that people who carry smartphones are, in essence, carrying documentation of their full lives, and they’re entitled to a reasonable expectation of privacy. To expose it, officers must first obtain a warrant.

The message, then, should be clear: keep your smartphone charged, and get ready to film. It could change the course of history.