Can a traumatic brain injury increase the odds that an individual will commit a crime? And if the answer is yes, should such an injury factor into how we judge people accused of crimes?

Those questions occurred to me when I read about the latest twist in the case of Aaron Hernandez, a former tight end for the New England Patriots, who had been convicted of murdering Odin Lloyd, a semi-professional football player who had been dating the sister of Hernandez’s fiancee. While on trial for Lloyd’s murder, Hernandez was charged with shooting and killing two other men, but was acquitted in 2017. Days after that he killed himself in his prison cell.

A team of Boston University researchers was asked to examine Hernandez’s brain. They reported that he suffered the most severe case of chronic traumatic encephalopathy — a progressive degenerative brain disease often seen in people with a history of repetitive brain trauma — they had ever seen in a person his age. While experts are using their customary scientific caution in not connecting Hernandez’s brain pathology to his crime, such severe injuries would have caused poor judgment and impulse control, two hallmarks of the bad behavior that landed Hernandez in prison for life.


If the fact that Hernandez’s brain was so damaged by his years playing football provides a partial explanation and a possible legal excuse for his actions, then we need to extend that to other people, especially our nation’s 2.2 million prisoners, in whom brain injuries are an extensive and unrecognized health problem.

Various correctional studies found that anywhere between 25 and 87 percent of inmates report having experienced a head injury. One study using the Traumatic Brain Injury Questionnaire conducted among 998 incarcerated men in Minnesota found that 83 percent of them had sustained one or more head injuries during their lifetimes. Gang members, in particular, were susceptible to these injuries. Some described an initiation ritual called “pumpkinhead” during which their heads were beaten until they swelled to look like pumpkins.

The numbers are even worse when it comes to female inmates. Women convicted of violent crimes are far more likely to have sustained a pre-crime brain injury than women in the general population. In one study, a high percentage of female prisoners described having 10 or more concussions prior to incarceration, often the result of domestic violence.

Given that the rate of traumatic brain injuries among prisoners is about seven times higher than it is in the general population, it’s time to consider that sustaining a head injury can put someone at higher risk of committing a crime.

Understanding the epidemiology of brain injuries is important for the justice system and how we judge people who are accused of crimes. A study about perceptions of traumatic brain injury patients published in the journal Neurorehabilitation last year found that people perceive the criminal acts of an individual with a traumatic brain injury as more excusable. Participants in the study understood that the morality of such individuals was changed by their injury and their crimes should be understood within that context and receive a reduced penalty. The injury reduces culpability because it’s avolitional, meaning it’s apart from personal resolve. Such an injury that causes problems in cognition and judgment is external to the person, and others can behold that individual as a victim.

There’s another reason why it’s important to know if incarcerated individuals have brain trauma. Such injuries are a complicating factor in how to rehabilitate prisoners, since the effects of a head injury can make it harder for an inmate to understand and follow rules. Their impairments may appear as indifference or uncooperative behavior when that isn’t the case.

Aware of the prevalence of brain injury among the prison population, the Centers for Disease Control and Prevention has recommended that inmates be tested and screened for these injuries as they enter confinement. That isn’t enough.

Screening individuals after they have been convicted comes too late and ignores the American legal tradition that responsibility for a crime is reduced when a defendant’s cognition is muddled by injury or illness. If we don’t bother to test defendants soon after they have been arrested, we may be ignoring their rights and violating the spirit of our laws.

Four states — Idaho, Kansas, Montana, and Utah — have abolished the affirmative defense of mental defect, meaning defendants in those states don’t have the opportunity to introduce evidence of brain injuries or mental impairment to disprove their guilt. The remaining 46 use some test to reduce the culpability of accused individuals if something was so wrong with their brains at the time of the alleged crime that they couldn’t form the requisite intent.

There are minor distinctions among these states. Twenty-five of them use what’s called the M’Naghten Rule, which requires the defendant to be able to know the difference between right and wrong in order to be morally and criminally responsible for his behavior. Twenty-one states use some form of the Model Penal Code Test, which examines whether the defendant could appreciate the criminality of his or her conduct and conform his or her behavior to the law.

The effects of head trauma — increased aggression and violence, diminished judgment and understanding — cut across all of the minor distinctions between states that allow an affirmative defense based on mental impairment. In short, some of the people with brain injuries who are living in America’s prisons probably wouldn’t be there if someone had bothered to diagnose them earlier.

The public’s biggest objection to expanding the use of a diminished capacity defense is usually that people can feign illness and lack of understanding, especially when they’re enticed to do so by a heavy punishment for an extreme and violent crime. But in that respect, head injuries are different than organic mental illness. Head injuries can be positively and objectively identified through CT scans and no one has to rely on the self-report of someone who’s at risk of losing a good part of his or her life to incarceration and may be motivated to malinger.

Moving the CDC’s screening recommendation earlier in the prosecutorial process — say when an individual is formally indicted — would help defendants get the health care they need. It would also help us avoid punishing them for crimes they aren’t morally or legally responsible for.

Courts should order mandatory CT scans for people accused of violent crimes. If the damage to a defendant’s brain is so severe as to prevent culpability, there is no justice in remanding that person to the same custody with people without these conditions, particularly since the average prison isn’t well equipped to handle inmates who suffer from head trauma.

Traumatic brain injuries among people in the criminal justice system are a public health problem that deserves more attention than it has received. Perhaps something good can come of Odin Lloyd’s death and Aaron Hernandez’s demise. We can focus more on understanding abnormal behavior — and looking for ways treat all victims justly — if we concentrate on brain injuries early on in the judicial process.

Chandra Bozelko served more than six years in a maximum-security prison. She is now a 2017 John Jay/Harry Frank Guggenheim Criminal Justice Reporting Fellow and writes the award-winning blog Prison Diaries.

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  • I have friend who is jail and has a sever head trauma but is I going to be send to state hospital and they are trying to make him take meds that he doesn’t need he doesn’t have mental illness he has been deemed incompent but they won’t let him fire her.he so confused we need help to plz get him out before they send him away to a mental hospital..can somone out there help.

  • Brain injuries canaffect behaviors, judgement impulse control,etc, to many grain injured folks end up in prison never getting treatment or proper care ,they are criminalized for something of which they have no control , I witnessed it first hand and its pity what we as a society do to these people, where they should be in treatment they are thrown in the pits of hell , again yes crimes can be committed ,but it’s as bad as throwing alzheimers in prison . It needs to be addressed by those better educated to do so mentally I’ll or damaged in mental institutions not prisons for years on end

  • yes i was in a altercation where i was hit on the top of my head spliting in wide open i remember loseing site and hearing and my whole body got hurt, right aftter this happened i was said to push some one in the arm , i can not recall doing this at all i cant even remember being transferred to hospital where they say i refused treatment was this or couldve been caused by the impact /trama to head from the force of being hit with bat ?? i later /4 to 5 hours later returned to hospital where they did a cat scan i believe they said no bleeding or swelling was found but to mich time had alapsed to stich/staple open wound this happened on 6/15/2018 since then i get bad head aches and light like the sun from being outside hurts my eyes the head aches are evry day some times they hurt real bad but they seem to always be there and noy go away

  • Not ALL head injuries are visible in CT scans. In facts, often certain type of brain injuries are not seen in standard MRIs or CT scans. There is a new technique called DTI that will show these brain lesions.

  • My son was hit in the head with a thick bottle right after that he had a domestic violence charge against him with his girlfriend of 6 yrs, never had an incident before with her.
    He was taken to the hospital and diagnosed with contusion to the brain, concussion. I need to find an attorney in az that will be familiar to the brain and crime.
    Can you help me?
    A mother in distress
    Gail Lawson

  • To me there is a question being ignored here: how can people with certain types of brain injuries be stopped from harming others or themselves? Is the answer institutionalization or constant care? If they cannot control their actions because of a brain injury, or if their impulse control is severely weakened or distorted, they are a risk to themselves and they may hurt or kill others. That conversation needs to play a central role regardless of whether these individuals are found guilty of intentional harm or not in a trial.

  • If you want to test a criminal for TBI go right ahead. But do not try and use it as an excuse for some thug killing or maiming someone, or breaking into a jewelry store and stealing a truck load of precious stones.

    • It can happen, and needs appropriate assessment and diagnosis, my look level 4 cousins hit by car was never the same ,his frontal lobe uh s CV completely dead lesions every where on brain ,coma 6 months was imprisoned for stealing vfc a girls car and other , was imprisoned for 4 years because he’s nuts

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