Lawyer Bryan Stevenson gives a first-person account of his decades helping marginalized Americans who have been unfairly and harshly punished by the U.S. criminal justice system, which disproportionately targets people of color and poor people. At the heart of Just Mercy is the story of Walter McMillian, a Black man who was framed for the murder of a girl named Ronda Morrison, convicted, and sent to death row. 

Stevenson alternates chapters about Walter with his personal reflections on our country’s history with racial disparity and issues around incarceration. Stevenson highlights other groups of vulnerable people who have been victimized by the criminal justice system and shares the stories of the prisoners he has helped over the years. The book also follows the growth of Stevenson’s nonprofit law project, the Alabama-based Equal Justice Initiative (EJI), through its expansion from focusing on death row prisoners to helping people sentenced to life without parole. Stevenson chronicles how EJI becomes a significant force in criminal justice reform.

In 1983 as a law student, Stevenson discovers his life’s passion when he interns with the Georgia-based Southern Prisoners Defense Committee and meets his first death row prisoner. After graduation Stevenson accepts a job with the organization to represent poor prisoners, including those in Alabama who lack any public defender. He meets Walter McMillian on Alabama’s death row. Walter owns a successful business but also transgresses racial boundaries when he has an affair with a white woman. Soon after the affair becomes public, the woman’s friend, Ralph Myers, accuses Walter of committing the unsolved murder of Ronda Morrison, which has outraged the community. Law enforcement, including a racist sheriff and the district attorney, eagerly pounces on this accusation, overlooking Walter’s alibi and a lack of evidence. Instead, they actively force Ralph to stick with his story even when he tries to recant. They coerce other false witness testimonies, and—as revealed years later—actively suppress evidence.

After Stevenson and the team at EJI unsuccessfully appeal Walter’s conviction, they launch their own investigation of the crime and uncover new evidence. They find witnesses who can prove the witnesses against Walter lied as well as financial records that indicate that one of these witnesses was paid to give false testimony. Stevenson and his team also petition for and receive all records from Walter’s trial. However, their big break comes when they receive a phone call from Ralph, who now wants to make amends. Ralph admits to lying about Walter and says he was threatened by law enforcement. Stevenson wins a hearing for Walter where he can present his new evidence: Ralph’s testimony, which is confirmed by health care workers and other inmates, as well as recordings of the law enforcement team threatening Ralph if he doesn’t frame Walter. 

While the judge refuses to grant Walter relief, Stevenson continues the appeal process through the Alabama courts. The district attorney asks outside agents to investigate the murder for which Walter was convicted, and the investigators determine that Walter had nothing to do with the crime. Six weeks later, the court invalidates Walter’s conviction. Stevenson and the State file a joint motion to dismiss the charges, and Walter is set free.

Throughout the process, Stevenson and Walter become close friends, and Stevenson helps Walter upon his release, including filing a civil suit on his behalf and offering him a place to stay. Walter works with Stevenson to share his story, giving interviews and speaking at legal conferences, and Walter is even featured in a documentary. Unfortunately, Walter is diagnosed with advancing dementia and is forced to rely on family and eventually a nursing facility for his care. He dies in 2013. Stevenson gives a eulogy at his funeral and shares all he learned from Walter, particularly that we must extend mercy to everyone, even those who have not earned it.

Interspersed with chapters chronicling Walter’s narrative are stories of Stevenson’s other clients and work. His closeness with these prisoners and their horrifying circumstances makes Stevenson more determined to help and causes him to reflect on abstract issues that nevertheless imbue the criminal justice system, like humanity and mercy. Stevenson focuses on several categories of vulnerable people who become trapped in the system, including mentally ill prisoners, disabled prisoners, and poor women who give birth to stillborn babies. 

Stevenson and his team at EJI also become increasingly focused on juvenile offenders who are sometimes tried as adults despite their young age. These offenders may be given de facto death sentences by being sentenced to life without parole and face perilous circumstances when they are housed in adult prisons. Stevenson illustrates how these prisoners retain their own humanity while being forced to live under inhumane conditions. He also discusses some of the qualities common among these types of prisoners: They are generally poor and disproportionately people of color, and most of them lack adequate legal counsel. The juveniles have horrific backgrounds of abuse and neglect.

Stevenson and his team at EJI also work to change the legal system to offer more protection to marginalized people. Several of his cases end up before the U.S. Supreme Court, and he succeeds in winning rulings that ban as unconstitutional the conviction of children to life without parole and the execution of people deemed incompetent from dementia or neurological disease. EJI works to raise public awareness of issues surrounding unfair incarceration, produces groundbreaking reports on racial issues, and sets up programs to help formerly incarcerated people adjust to life on the outside.

Stevenson also reflects on the issues that surround the criminal justice system. His time spent with prisoners awaiting their execution makes him realize how inhumane it is to prepare another human to die. After decades of work, when Stevenson fails to prevent the execution of a man who suffers from an intellectual disability, he momentarily feels unable to continue his work. However, he realizes that he cannot help but be broken by his experiences and comes to understand that it is his own brokenness that allows him to more fully understand the need for mercy and to bring compassion to others. The book ends with Stevenson’s renewed commitment to helping others.