Lindsay Clancy Was Mentally Ill. But Was She Legally Insane?

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.