Sometime this autumn, a St. Louis County grand jury will decide whether to charge Ferguson, Mo., patrolman Darren Wilson in the death of Michael Brown in August. If the case does go to trial, its meaning is almost sure to narrow. No longer will it be about the dangerous ways race has mixed with the militarization of the nation’s police forces or the toxic effect of building municipal budgets on fines for petty crimes. In court, the only question will be whether officer Wilson had cause to open fire.

That’s the problem with using the criminal court as a site of racial reckoning, argues Oberlin College history professor Renee C. Romano in her insightful new book on the cold cases of the civil rights era. In the 1950s and ’60s, Southern white supremacists met African American activism with ferocious violence. But the perpetrators were rarely brought to justice, no matter how appalling their crimes. Twice all-white juries refused to convict Byron De La Beckwith of assassinating the NAACP’s Medgar Evers in June 1963, though his fingerprints had been found on the gun sight he’d left at the scene. And Alabama authorities didn’t even bring murder charges against the Klansmen who killed four little girls in the September 1963 bombing of Birmingham’s 16th Street Baptist Church. Instead they were convicted of possessing dynamite without a permit, an offense that carried a $100 fine.

For decades the cases remained closed, despite family members’ efforts to pry them open. Then, in 1989, Myrlie Evers finally persuaded the assistant district attorney of Hinds County, Miss., Bobby DeLaughter, to revisit her husband’s murder. It took five more years to convict Beckwith. Once the verdict was in, though, the South’s cold cases suddenly became hot: Between 1989 and 2012, prosecutors investigated more than 125 civil-rights-era murders.

Only a handful of those investigations led to indictments, Romano points out. And those tended to come in what had been high-profile cases, presumably because the evidentiary trail had been well preserved. Still, the results were stirring. In May 2000, Alabama authorities arrested two of the Birmingham bombers on the murder charges they’d dodged in 1963. Four years later, a grand jury in Neshoba County, Miss., indicted one of the Klansmen who killed civil rights workers James Chaney, Mickey Schwerner and Andrew Goodman in the summer of 1964. And in 2007 an Alabama grand jury did the same with the state trooper who gunned down Jimmie Lee Jackson during the 1965 Selma campaign, the tragic prelude to the movement’s fabled march over the Edmund Pettus Bridge.

Having reopened old wounds, though, prosecutors salved them in a particular way. First they did their best to limit the trials’ racial meaning. This wasn’t “a civil rights case that just incidentally involves a murder,” DeLaughter told the jury at the start of the Beckwith trial. It was a murder case pure and simple, centered on the cowardly killing of a good man, a crime “every decent human being should be sickened by.”

‘Racial Reckoning: Prosecuting America's Civil Rights Murders’ by Renee C. Romano (Harvard Univ.)

Then they homed in on the defendants’ extremism — the vicious racism they professed, the Klan memberships they proudly proclaimed, the acts of terror they bragged of committing — turning them into “the human equivalent of a cockroach,” as one of the defense lawyers put it. These were the men who had tarnished the South’s reputation back in the 1960s, the prosecutors concluded. Now the region could be redeemed from their sins, the stains of the past wiped clean, if only the jurors had the courage to convict them.

But it wasn’t that simple, Romano argues. Of course the defendants were fanatics, driven by hatreds so deep it’s hard not to see them as psychotic. They were also products of a social order that depended on the brutality that men like Beckwith and the Birmingham bombers embraced, even as the better sort looked away. By building their cases on individual culpability rather than communal responsibility, prosecutors obliterated that critical context. Not that they had much choice. Romano readily admits that the cold-case trials were shaped partly by the restrictions the courts imposed — judges simply weren’t going to let prosecutors introduce evidence that didn’t bear directly on the defendants’ actions — and partly by the state’s reasonable assumption that it was better to try a human cockroach than a racist social system. In the end justice could be served. But it was justice of a very particular sort.

The Ferguson trial, should there be one, won’t play out exactly as the cold cases did. Wilson isn’t a Klansman, after all. By all accounts he’s an ordinary suburban cop who, until Aug. 9, didn’t have a single mark on his record. But he worked in a town that’s been battered by white flight and economic decay. Ferguson’s poverty and unemployment rates are twice what they were 14 years ago. Its property values have spiraled downward. And its tax base has crumbled: Last year expenses outstripped revenue by $7.3 million, a gap the white men who control the local government have tried to fill by borrowing — this year Ferguson will pay $2.88 million just to service its debt — and by ratcheting up fines that fall disproportionately on the town’s African American population. Those dynamics didn’t make officer Wilson shoot Brown. Without taking them into account, though, that terrible moment is reduced to a tragic encounter between two young men on a suburban street, driven by whatever emotions and demons they carried with them. As Romano’s insightful book makes clear, that isn’t enough.

Kevin Boyle teaches history at Northwestern University. His book, “Arc of Justice: A Saga of Race, Rights and Murder in the Jazz Age,” received the National Book Award for nonfiction.

RACIAL RECKONING

Prosecuting America’s Civil Rights Murders

By Renee C. Romano

Harvard Univ. 268 pp. $35