Just Mercy is a thoughtful meditation of the nature of compassion and cruelty. It’s a startling reminder that human beings are capable of both extremes. The film has been adapted from the memoir of Bryan Stevenson, a Harvard-trained lawyer, who moved to a small town in Alabama in 1989 to review charges against death row inmates. 
Here's Anupama Chopra's review of Just Mercy, directed by Destin Daniel Cretton.