SJC Expands Insanity Defense to Include Substance Use

The state's highest court unanimously vacated the murder conviction of a man who killed a fellow patient while in a psychiatric ward, saying the jury should have been given clearer instructions about the insanity defense and substance use.

The State Supreme Judicial Court ruling, written by the late Chief Justice Ralph Gants, ordered a new trial for Aldo Dunphe, convicted of killing Ratna Bhattarai in 2013. Both men were patients in the psychiatric ward of UMass Memorial Medical Center in Worcester.

Dunphe's murder trial focused on whether he was criminally responsible for the crime because of mental illness and his near-constant cannabis use.

According to the ruling, a defense expert testified during trial that Dunphe has schizophrenia and was delusional when he killed Bhattarai, claiming the victim was his biological father and was trying to harm him.

A prosecution expert testified that Dunphe suffered from from a "substance-induced psychotic disorder and a cannabis withdrawal condition" that resulted in hallucinations, but not schizophrenia. The prosecution said Dunphe was in control of his thoughts at the time of Bhattarai's killing and therefore was criminally responsible.

Gants ruling says juries can consider the the intersection of mental illness and substance use when weighing the actions of a defendant.

"A drug-induced mental disease or defect still constitutes a mental disease or defect for purposes of a criminal responsibility defense," Gants wrote.

But Gants also said that substance use alone does not qualify for the defense.

"Intoxication from alcohol or the high from drugs is not a mental disease or defect where the loss of capacity ends when the effects of the alcohol or drug wear off; a mental disease or defect is something more enduring, reflecting something about the person's brain chemistry that, although perhaps not permanent, is more than the transient effect of the person's substance use," he wrote.

Voluntary intoxication alone — and someone using substances knowing they will exacerbate a mental illness — would not make a defendant eligible to cite a lack of criminal responsibility defense, Gants wrote.
The ruling also says Dunphe's trial was flawed because jurors did not consider the possible connection between marijuana consumption and mental illness, even though that is not a settled topic among researchers.
The SJC ruling says new language will be used for jury instructions to clarify the mental illness and substance use and the lack of criminal responsibility defense.


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Deborah Becker Host/Reporter
Deborah Becker is a senior correspondent and host at WBUR. Her reporting focuses on mental health, criminal justice and education.



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