If you have not seen Netflix’s breakout documentary series “Making a Murderer,” there is a good chance every other person you know has.

The series follows the intellectually challenged 16-year-old Brendan Dassey and his uncle as they are ushered through the Wisconsin criminal justice system. Brendan’s intellectual or cognitive disabilities have been mentioned numerous times, but how his age and disability mix with interrogation techniques and self-advocacy within the system have not been explored.

Public outrage occurred over the suggestive, and at times directive, methods police used to obtain Brendan’s confession later used in court.

Brendan, who did not even know the word “inconsistent” when police used it, is reported by the entertainment news site Vulture to have an IQ ranging from 69-73, which in many other states could make him mentally incompetent to stand trial.

This cognitive disability is not to be confused with mental illness, which may impact half of incarcerated adults and can be treated by medication or therapy. Brendan is also just one of almost 400,000 inmates with cognitive disabilities currently imprisoned in the United States.

A December 14, 2015 report from the Bureau of Justice Statistics shows just how “consistent” the incarceration of cognitively disabled individuals is in the United States, identifying that roughly a quarter of detained Americans struggle with a cognitive disability.

Cognitive disorders are constant, permanent, and include such conditions as Down syndrome, autism, dementia, learning disorders and traumatic brain injury. Cognitive functioning affects how someone understands and processes information. More importantly, cognitive impairment affects how someone might respond to requests or pressures from other people–for instance, the police.

“Making a Murderer” portrayed the story of just two out of what the Prison Policy Initiative* counts as over two million people incarcerated in the United States.

The Justice Bureau’s report used data from the 2011-2012 National Inmate Survey to examine “Disabilities Among Prison and Jail Inmates.” It found roughly two in 10 prisoners and three in 10 jail inmates suffered from a cognitive disability. This means that 19 percent of people in prison and 31 percent of those in jail have serious difficulty concentrating, remembering, or making decisions, just like Brendan.

As a comparison, less than 5 percent of the general population suffers cognitive disabilities, but nearly 20 percent of state and federal prisoners do.

Among female inmates, an often ignored but growing prison demographic, cognitive disabilities were also more common than among their male counterparts.

Particularly alarming was the bureau’s acknowledged limitation of their data due to uncounted inmates whose cognitive disabilities were so severe they could not properly consent to the study.

Netflix viewers were also shocked to see Brendan being treated so harshly as a 16-year-old (with mental functioning of an even younger child), but treating children as adults in criminal proceedings is the norm across the United States.

He was just one of what the National Juvenile Justice Network counts as 250,000 juveniles tried as adults each year. However, The Campaign for Youth Justice found that, unlike Brendan, most youth tried as adults are being prosecuted for non-violent offenses, not serious, violent crimes.

The type of crimes, or age at which a juvenile is transferred to the adult system, varies widely state-to-state and may be controlled by statute, such as the New York law requiring anyone over 16 to be tried as an adult, or by discretion of the state prosecutor or judge assigned to the case.

Juveniles may also be convinced by the state to voluntarily accept an adult sentence in lieu of juvenile delinquency under the premise that they will actually serve less time. This option comes with consequences such as an adult criminal record, publicly available records, fewer educational services in detention and the physical danger of being a child housed with adult criminals.

Although all age groups in the December report from the Bureau of Justice Statistics were equally likely to experience cognitive disability, juveniles with cognitive disabilities suffer the additional barrier of still developing. Among healthy non-disabled youth, the brain’s development does not complete until the mid-twenties, with complex reasoning and decision-making being the last abilities finalized. This means that cognitively disabled juveniles have two meaningful disadvantages when they arrive in the adult criminal justice world, making it difficult or impossible for them to advocate for themselves or adequately protect their own interests.

While everyone has a different theory on Brendan’s innocence or guilt, almost everyone agrees that he was unable to understand what was going on around him. Like so many youth and cognitively disabled adults, Brendan is serving time, in his case a life sentence, after interrogations and a trial he could not adequately comprehend. His experience demonstrates what nearly half a million men and women face in a legal process designed to get convictions, rather than the truth. Brendan is just one boy, but every day the United States is disproportionately punishing the cognitively disabled and young people still developing cognitive skills.

*This story has been updated; the previous version cited the Vera Institute of Justice rather than the Prison Policy Initiative.

Courtney Knight, Master in Social Policy candidate – Courtney earned a Bachelor of Science in Sociology from Saint Joseph’s University in 2011, having completed a thesis on Violence in Music and Juvenile Violent Crime. She spent two years working with homeless & foster youth in Pennsylvania, where she was a member of the Bucks County Direct Service Coalition and worked with the state Budget Coalition. In preparation for her legal studies, she became a paralegal at a personal injury firm in 2013, where she continues as a law clerk today. Courtney is concurrently pursuing a Juris Doctor at Rutgers University School of Law, and a Master of Science in Social Policy at The University of Pennsylvania, where her research concentrates on Juvenile Justice Reform.

This story has been published in partnership with the University of Pennsylvania’s School of Social Policy & Practice (SP2). In the run up to the 2016 Presidential Election, the school launched “SP2 Penn Top 10, a comprehensive multimedia initiative in which renowned SP2 faculty members analyze and address the most pressing social justice and policy issues.”

Part of the project is the creation of stories produced by “SP2 Penn Top 10 Fellows,” graduate students from the School who are trained in solution-based journalism using the Journalism for Social Change curriculum.