You probably saw the video that went viral a few days ago -- the one where a Los Angeles cop fires five rounds in a struggle with a homeless man in the center of downtown's Skid Row, as horrified onlookers watch. The video was viewed hundreds of thousands times before it was pulled by Facebook, and many viewers were shocked by what they felt was an excessive show of force. The L.A. police say the unidentified man known as "Africa" was shot because he was in the process of grabbing  the officer's gun, and in this open case we'll  have to see if more evidence backs up their account.

But the Los Angeles case also showed, dramatically, how the ease of filming and uploading videos in the 21st Century has changed the way that we view the police and how they do their job. Just a few years ago, before smartphones, the LAPD would have simply released a short press release about "a justifiable shooting," the L.A. Times would write an 8-inch story based on the police version, and that would be the end. But when we can see what really happened, we begin to ask questions. Did it really have to go down this way? How does a situation become so lethal so quickly? Why does the United States have many, many more times police-involved shooting than other developed nations?

Thanks to video, we now know that when the police and other civic leaders -- folks we so desperately want to trust -- provide us with basic information about these emotionally charged incidents, they are so often not telling people the truth. On Staten Island, we saw the film where an officer slams Eric Garner to the ground in a confrontation over the beyond-inconsequential crime of selling loose untaxed cigarettes, then murders him with a banned choke-hold -- and yet no one was charged. In Cleveland, we saw footage that showed the killing of a 12-year-boy with an air gun, Tamir Rice, take place in a matter of split seconds, nothing like the initial police account. Right here in Philadelphia, police told the public that a man who was gunned down by police, Brandon Tate-Brown, was pulled over for driving with his headlights off -- until the video showed his headlights were very much on.

Then we have the the killing of unarmed 18-year-old Mike Brown in Ferguson, Mo., last August -- the death that spawned a national protest movement with the tagline #BlackLivesMatter.

Compared to the other high-profile police-involved killings, there was no video as Officer Darren Wilson confronted Brown and his friend in the middle of an empty street in Ferguson. The only film we had from the scene was the footage that showed a young man's uncovered bullet-riddled body and its inhuman treatment, left to fester in the hot Midwestern sun for four-and-a-half endless hours. To get to the truth of how Brown died, Ferguson -- and a riled-up nation -- would have to trust the local authorities to investigate and work in the interest of the citizens.

As chronicled on this blog and elsewhere for the last seven months, the local authorities in Ferguson and St. Louis County did everything possible to abuse that trust. When citizens took to the streets of Ferguson to ask questions and air their grievances, they were met with police dogs -- shades of Birmingham in 1963 -- then tanks and mounted weapons, then assaulted with tear gas. The Ferguson police chief withheld Wilson's name until he released -- on bogus pretenses -- a video meant to impugn the victim. The district attorney, Robert McCulloch, took the case to a grand jury without recommending charges -- a legal break for Officer Wilson afforded none of the other thousands of suspects his office prosecutes who aren't cops. Then, in the most stunning development of all, McCulloch admitted he knowingly put on the stand a witness who was not telling the truth.

Completely lost in all this was what Brown's family and the people of Ferguson wanted -- justice -- and what that justice looked like: A jury trial, where the facts of the case would be aired in public, under oath. (A similar outcome , in other words) to what happened in the Trayvon Martin case in  Florida.) Since McCulloch and the corrupt political establishment in greater St. Louis were determined to thwart real justice, America got the best thing it could: A civil rights investigation by the U.S. Justice Department, even though the high bar for civil rights charges against Wilson were virtually impossible to clear.

As expected, the Justice Department announced today that Wilson will not be charged. But its investigation did much, much more to inform the public than McCulloch's biased pseudo-probe. Their work concluded there's no way to disprove Wilson's assertion that he feared for his life, that blood stains show Brown was moving back in the direction of Wilson when the fatal shots were fired, and that while accounts vary, his arms were probably outstretched or down at the end of his life, not up in the air.

I still have a lot of unanswered questions about what happened that Saturday, but this may be as close to the truth as we'll ever get. I still believe that if there had been video of the killing of Mike Brown, we would be every bit as shocked and upset as we are to watch the footage of the killings of Tamir Rice, Eric Garner, "Africa," and others. But we also learned a much deeper truth yesterday, in a separate report by the Justice Department -- which explains why so many Ferguson residents took to the street when Brown was shot, and why there was persistent doubt from Day One about what really happened.

Because we now know that the police and civic leaders in Ferguson had been abusing the public's trust for years before Mike Brown's fateful walk down the middle of Canfield Drive, and in some of the worst ways possible.

"Seen in this context, amid a highly toxic environment, defined by mistrust and resentment, stoked by years of bad feelings and spurred by illegal and misguided practices, it is not difficult to imagine how a single tragic incident set off the city of Ferguson like a powder keg," outgoing Attorney General Eric Holder said in releasing the findings.

That context, that legacy of racism and abusive practices within law-enforcement in the St. Louis suburb, is staggering. The Justice Department report found that while blacks comprise 67 percent of Ferguson, they are 93 percent of people arrested there, and that for oney two-year period only black people were charged with resisting arrest. City officials used law-enforcement as a way to raise revenue for Ferguson instead of the supposed goal of public safety, and in one case a woman who parked her car illegally once in 2007 ended up paying more than $1,000 in fines and spending six days in jail. Black residents were harassed or even assaulted by police officers while waiting for a bus, sitting in a car after a game of basketball, or walking across the yard to where a girlfriend was staying. Every single reported case in Ferguson of someone bitten by a police dog was African-American. The report notes that court and police officials who suggested that poor blacks abused the system in fact frequently allowed each other to evade tickets and citations. And then there's the racist emails by unnamed city officials insulting President Obama, Michelle Obama, everyday black and Muslims, and so on and so forth.

And yet as I write this, Ferguson police chief Tom Jackson still has his job. That's beautiful.

Meanwhile, every American should read the Ferguson report, and remember this. It's easy to dismiss Ferguson as the bad boy, the outlier, the exception...except that it's not. To the contrary, the actions and attitudes exposed in this one Missouri town -- over-militarized robo-cops treating citizens as a colonial Other, greedy pols milking the municipal code as a cash cow, and law enforcement spitting in the face of accountability -- permeate policing in America from the Florida Keys to the Bering Strait.

Just think about some of the headlines in just the last few days.In Cleveland, city officials blamed 12-year-old Tamir Rice for causing his own death. In New York, a deputy police commissioner complained in a tweet that mentally ill people "off their meds" were "w[a]lking into bullets." In Philadelphia, there were allegations that police aren't keeping their promises to curb stop-and-frisk harassment of blacks and Latinos. Across the river in Bridgeton, N.J. a peaceful protest of a police shooting was met with a ridiculous show of force. And so on and so on. The stories differ but the underlying problem is always the same: Lack of respect, if not outright contempt, for the public that law enforcement is supposed to not only protect but actually serve.

The heartbreaking irony is that these abuses poke a giant stick in America's eye just as the nation celebrates the 50th anniversary of arguably its greatest civil-rights triumph -- the 1965 Selma protests and the Voting Rights Act that emerged in their wake. As the popular movie "Selma" demonstrates, the movement's work was hard, seemingly impossible at times, but the goal was also disarmingly simple: Allow black people to vote.

Unfortunately, I doubt that one law, or even a series of laws, would solve the nation's current crisis in policing. To be sure, some measures would help greatly -- independent prosecutors for police shootings and brutality, body cams, conflict resolution instead of the world's worst incarceration rate, ending "the war on drugs," for starters. But the real fix is not changing a law but somehow changing attitudes, a much, much harder task. Yet for America to go forward, we must overcome.