Transcript for Oscar-nominated '13th' documentary's provocative message
??? America has more people behind bars with per capita than any other country on Earth. And a disproportionate number of those inmates are African American. A new documentary argues mass incarceration is simply slavery by another name. Tonight juju Chang sits down with the film's director. We now have more African Americans under criminal supervision than all the slaves back in the 1850s. Reporter: Mass incarceration as modern day slavery. The provocative message of the oscar-nominated film "13th." The constitutional amendment abolishing slavery. What you got after that was a rapid transition of mythology of black criminality. The kinds of kids are called super predators. Millions of dollars will be allocated for prison and jail facilities. Three strikes and you are out. Reporter: The documentary explores the impact of decades of law and order politics and a prison industry that director ava duvernay says profits off punishment. Slavery, reconstruction, Jim C crow, the drug wars, the Reagan years, the Nixon years, the Clinton years and then the prison boom and how it mushroomed. Reporter: Now one of the most powerful women in Hollywood. What happens when a man stands up and says enough is enough. Reporter: Her critically acclaimed movie "Selma" -- I enjoy my days. Reporter: She grew up miles from Hollywood and yet a world away from Compton in the '80s. Gang violence, racial tension and harsh policing, an everyday reality. Most people think safety, protection when they see an officer. I thought fear. I started to put that fear and what I've learned about marginalized people together. Reporter: Her personal history infused in her latest film release otd Netflix. One out of four people with their hands on bars are locked up here in the land of the free. Reporter: 2.2 million people are behind bars in the U.S., nearly 60% people of color. Gore is one of the voices advocating prison reform. As a teenage drug dealer, she shot and killed a man. I'll never forget. There's constant reminders. Reporter: Today he says he's filled with remorse of the two decades he spent in prison, his nearly seven years in solitary were akin to torture. It was by far, the most barbaric experience I've ever encountered in my life. The smell of human defecation and urine and despair and hopelessness. Reporter: He said this letter from his son was a ray of light in the darkness. I pray and pray one day my prayer will come true, and we'll be together for life. Reporter: Now a best-selling author, he says prisons are filmed with young black men. A point the film echoes. The system cannot exist if everyone decides to go to trial. If everybody insisted on a trial, the whole system would shut down. What typically happens, the prosecutor says, you can make a deal and we'll give you three years, or you can go to trial and we'll get you 30. You want to take that chance? Feel free. Nobody in the hood goes to trial. Reporter: 16-year-old khalif, a tragic case in point. Khalif was charged with a really petty crime that it turns out he didn't commit. Reporter: A case "Nightline" covered in 2015. Falsely accused of stealing a backpack, he refused to plead guilty. They told me I would be released that same day if I said I did. But I didn't do it. Reporter: Since his family couldn't afford bail he ended up in rikers island jail. That's him on the floor, beaten by a gang of prisoners, captured on surveillance video, obtained by "The new Yorker" magazine. It was like hell on Earth. We were beaten, stomped. By the correction officers. They was just beating on me. They was just beating on me. Reporter: Without being given a trial, never convicted of a crime, he spent most of his three years behind bars in solitary confinement. Until finally all charges were dropped, but the psychological damage has taken its toll. Within two years, he committed suicide. How many khalifs are out there? I feel like he was a martyr. His voice rang out, to shed light on this epidemic. Reporter: Duvernay acknowledges politicians on both sides of the aisle has evolved in their thinking. It's an enormous burden on the black community, but it violated a sense of fairness. Reporter: But she expresses serious concerns about our new president. In the central park jogger case, they put five innocent teens in prison because the public pressured to lock up these animals was so strong. You better believe that I hate the people that took this girl and raped her brutally. You better believe it. Donald Trump wanted to give these kids a death penalty. He took out a full-page ad to put the pressure on. These children, four of them under 18, all went to adult prisons for 6 to 11 years, before DNA evidence proved they were all innocent. Reporter: Even though their convictions were overturned and they were given a $40 million settlement from the city, just weeks before the election, trump doubled down, telling CNN, the fact that the case was settled with so much evidence against them is outrageous. The central park five case was a case that was used to really examine that myth of criminality, and it was exacerbated by these hysterical voices such as Donald Trump at the time. A lot of people point to that as a racist act. Sure, of course. Absolutely. It was an early indicator and he's done nothing but be consistent in his views and rhetoric. Do you think Donald Trump's racist? I think he is. Reporter: President trump has denied accusations like this, telling a local NBC station in 2016 -- I am the least racist person you've ever met. I love it, I oflove it, are we having a good time? Reporter: But duvernay crafts her argument in a controversial scene weaving together trump's campaign rhetoric to footage from the civil rights era. When they protested once, you know, they would not do it again so easily. I'd like to purchanch him in the face, I'll tell you that. I love the old days. You know what they used to do to guys like that, when they were in a place like this? They'd be carried out on a stretcher, folks. I am the law and order candidate. It's the same rhetoric, it's the same racist language. It's the same toxic environment that he creed created at those rallies. Reporter: Her point may be up for debate, but few deny the nightmare of mass incarceration. A dark truth that duvernay may spin into Oscar gold. I'm juju Chang for "Nightline" in Los Angeles.
This transcript has been automatically generated and may not be 100% accurate.