The Monroeville, Alabama of “Just Mercy” is a barely-repentant racist town coasting on the righteousness of its most famous resident, Harper Lee — who wrote “To Kill a Mockingbird.”

“Hav’ya BEEN to the Harper Lee Museum?” every white person in the legal system asks Bryan Stevenson, an African American “lawyer from up North,” upon his arrival. It’s the late 1980s, and he has brought his Harvard Law degree to the Deep South to work for death row inmates, to provide “legal assistance for people who can’t afford it.”

But the comfy white folks of Monroeville are bound to be puzzled, if not enraged, by that. “To Kill a Mockingbird!” they say, as if that makes them safe and secure from present day scrutiny and condemnation. The book was set in the 1930s, came out in 1960, and heck, Gregory Peck was in the movie! All that lynching, racism, racial profiling and unequal justice? Ancient history!

“Just Mercy” is a movie about a touchstone case that proved that to be a lie, a righteous, well-intentioned but uneven emotional roller coaster of a film that plays it safe a little too often itself.

Michael B. Jordan plays Stevenson, an idealist fresh out of law school with a government grant to start a legal aid service for inmates in the heart of the former Jim Crow South. He has been chastened by his internship, helping the same sorts of clients he will be dealing with in his new job. But he’s raring to go. Back home in Delaware, his mother is less optimistic, blunt about her concern that he might “get killed down there.”

Stevenson’s ardor is cooled when he finds his new office manager (Brie Larson), a white local, can’t even rent office space for such a “business.” His first visit to prison includes a protocol-breaking strip search, meant to simply humiliate him.

Jordan lets us read that it in Stevenson’s eyes, the struggle to stay poker-faced at the insults, threats and violent police harassment that follow. It takes a special kind of commitment to endure that, Jackie Robinson stoicism and self-control coupled with calming righteousness.

Meeting his first clients, he is steeled for the task ahead. He needs to be. Because while he can assure a condemned man (Rob Morgan, superb) whose Viet Nam War-related post traumatic stress syndrome means “there’s always something we can do” to build an appeal, while the holes in another convicted murderer’s case make a retrial an obvious path, Stevenson is about to figure out how little has changed in the Alabama legal system since Lee’s Atticus Finch stood before the court.

The film’s prologue shows us Walter “Johnny D.” McMillan’s arrest. Driving home from his wood pulp business, Johnny D. (Jamie Foxx) smiles through the “sharp looking truck you got there” cracks, the implied threat and then summary arrest for a teenage white girl’s murder. Now, he sits on death row, broken and furious, not really wanting to put his family through the false hopes this Harvard lawyer with “white boy status” is promising.

“I look like a man who could kill somebody,” he says. Down here, “you guilty from the moment you born.”

The ups and downs of McMillan’s case, the smiling dismissals of the green, don’t-rock-the-boat district attorney (Rafe Spall), the intimidating scowls, manipulations and unspoken menace of the sheriff (Michael Harding), an entire system that circles the wagons to defend itself from outside scrutiny, second guessing and reform, are the meat of “Just Mercy.”

As such, it’s a generally unsurprising film, given the years of high-profile police and prosecutorial misconduct cases that have played out in the news, the trigger-happy, racial profiling local police who inspired #blacklivesmatter. In 1988 Errol Morris released “The Thin Blue Line,” a classic documentary about a Texas case not unlike this one, but lacking the racist undertones here. This is nothing new, and yes, too little has changed.

Director and co-writer Destin Daniel Cretton (“The Glass Castle,” “Short Term 12”) never lets the picture turn preachy and didactic. But he’s hard-pressed to escape the tropes of the genre, seen in movies from “Dead Man Walking” to “Clemency,” both better films — the death row shouts of support and rattling of cups against the bars whenever one of their number is in the death chamber, the “traffic stop” by police and anonymous threats by phone meant to scare off those who question “the way things have always been.”

Characters are thinly-developed and some — Johnny D’s wife (played by Karan Kendrick) among them — are mere archetypes.

The performances are generally solid, with Foxx reminding us his Oscar was no fluke, although fellow Oscar-winner Larson appears to be picking up a cigarette for the first time. Tim Blake Nelson, playing an inmate and key prosecution witness, gives a dazzling character turn.

Jordan, in the sort of role usually offered to Chadwick Boseman, gets across the earnestness and dignity of the character without letting us forget he’s human and a bit alarmed at all this Jim Crow Era behavior coming from The System and those amoral enough to defend it.

My favorite moment in the movie is the one that gives it purpose. We’ve seen judges simply refuse to consider that they and their system have made a mistake, but it takes the venal sheriff to suggest why no “lawyer from up North” is worth hearing out. To guys like Stevenson, “we’re just’a bunch’a corrupt, Southern racists,” as if declaring that out loud makes it untrue.

But that “racists” and “bigots” and “bigotry” exist isn’t really the message of “Just Mercy.” And that’s not because the words don’t pop up, here and there, and aren’t apt and deserved. It’s just that there’s nothing teachable in such labels.

“Prejudiced,” as evidenced by the behavior — personal, official and legal — in this case and many others like it, is what “Just Mercy” sees as instructive. Break down the word. “Prejudiced” implies “pre-judged,” which is the curse of our legal system — under partisan assault, courts stuffed with judged deemed “unqualified” but fitting the racial and political agenda of those doing the appointing.

Under such conditions, there will never be a day when an Atticus Finch or Bryan Stevenson isn’t a lonely voice in the wilderness, crying out for justice for those railroaded, ineptly-defended, bankrupted, broken and imprisoned by a system set up to do just that, from Jim Crow onward.

MPAA Rating: PG-13 for thematic content including some racial epithets.

Cast: Michael B. Jordan, Jamie Foxx, Brie Larson, Rafe Spall, Tim Blake Nelson, O’Shea Jackson Jr., Karan Kendrick, Michael Harding and Rob Morgan

Credits: Directed by Destin Daniel Cretton, script by Destin Daniel Cretton and Andrew Lanham, based on the book by Bryan Stevenson. A Warner Brothers release.

Running time: 2:16