These are the facts that no one disputes: On January 24, 2023, Lindsay Clancy strangled her three young children to death, then she attempted suicide by cutting her wrists and neck and jumping out of a second-story window in her Massachusetts home, which left her paralyzed from the waist down. The point of contention, as her trial has progressed, is whether Clancy should be held criminally responsible for her actions.
Clancy has entered a plea of not guilty by reason of insanity. A jury will soon decide whether she was sufficiently mentally ill at the time of the murders to spare her a mandatory sentence of life without parole in a state prison. The problem for Clancy and her defense team is that although she appears to have been extremely sick in the months leading up to the tragedy, the jury may still find her legally sane. This is because the legal standard for insanity diverges from the clinical understanding of mental illness.
Insanity defenses, which are premised on the idea that people are not fully blameworthy for criminal acts that could be seen as outside their control, have existed since ancient Greece and Rome and have been a feature of jurisprudence for hundreds of years. The legal definition of guilt typically requires both action and intention, which means committing a crime while in a reckless, negligent, purposeful, or knowing state of mind. An insanity plea is premised on the assumption that people who are insane at the time of their crimes do not have the capacity for criminal intent, so they cannot be considered entirely guilty.
Christopher Slobogin, a professor of law and psychiatry at Vanderbilt Law School, told me that courts have applied different tests for establishing insanity over time, though none has overlapped fully with clinical descriptions of mental illness. In the Victorian era, courts seeking to determine whether a defendant could be excused from criminal liability by reason of insanity began relying on something called the M’Naghten rule, named for Daniel M’Naghten, a Scottish artisan whose paranoid delusions about a grand conspiracy moved him to shoot and kill a senior British civil servant in 1843. M’Naghten’s case inspired a rule that designated defendants legally insane if they did not understand the nature of their criminal acts or that their actions were wrong. This rule remains in use in roughly half of the United States.
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According to Michael Perlin, an attorney and a professor emeritus at New York Law School, the insanity defense became controversial in the United States after the acquittal of John Hinckley Jr., whose defense attorneys had argued that his attempted assassination of President Ronald Reagan in 1981 was a consequence of his schizophrenia and delusional obsession with the actress Jodie Foster, whom he wanted to impress. Outrage swiftly followed the 1982 verdict, stoked by politicians who called trial-jury members before a Senate subcommittee to interrogate them about their decision. Idaho’s legislature promptly eliminated the insanity defense that year, followed by Utah in 1983 and Kansas in 1995. Congress passed the Insanity Defense Reform Act in 1984, which narrowed the application of insanity defenses in federal cases.
In states that kept the insanity defense, views on how to apply it have continued to evolve. The closures of mental-health institutions across the country in the 1960s and ’70s increased the number of mentally ill people in the criminal-justice system, which created some urgency for establishing an adequate standard for legal insanity.
By defining insanity in terms of what a defendant knew at the time of the crime, the M’Naghten rule excluded defendants who had understood their conduct was wrong but nonetheless had been unable to resist or control their impulses. Some states addressed that limitation by expanding insanity defenses to include defendants who had acted under an irresistible impulse caused by mental illness or who had been otherwise unable to abide by the law. In Massachusetts , defendants may be found not criminally responsible if a mental illness left them unable to appreciate the wrongfulness of their conduct or unable to conform their conduct to the requirements of law.
In the months prior to what Clancy’s defense team has described as a psychotic break, she had repeatedly sought psychiatric help. She was briefly hospitalized and had prescriptions for 13 medications to treat her intense anxiety, depression, racing thoughts, insomnia, and confusion. Her lawyers have argued that she was suffering from postpartum psychosis , a psychiatric condition that occurs after 0.1 to 0.2 percent of deliveries in women who don’t have a history of mental illness. At the time of their death, her children were eight months to 5 years old.
According to Veerle Bergink, the director of Mount Sinai’s Women’s Mental Health Center, postpartum psychosis is an acute episode of psychosis, mania, or psychotic depression in the months following childbirth. Symptoms include severe mood disturbances, delusions, hallucinations, confusion, and catatonia, and patients generally lose touch with reality. Bergink told me that a woman may come to believe that all the wars in the world are her fault, or that her child is possessed by an evil spirit. Because mothers diagnosed with postpartum psychosis are at heightened risk of suicide and infanticide, the condition is considered a psychiatric emergency.
Clancy’s desperate diary entries dated from the days and weeks before the murders recount such symptoms. She described feeling “incredibly sad and guilty” about not breastfeeding and suffering from “crazy brain fog.” She wrote that she was living “moment to moment waiting for the next nap time,” terrified that her infant son was becoming overtired, “because I feel I can’t help him.” She admitted to contemplating suicide. “I feel like I’m...