Commonwealth v. Dipadova (2011)

Voluntary consumption of alcohol or substances and criminal responsibilty

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“A defendant’s lack of criminal responsibility must be due to a mental disease or defect. Intoxication caused by the voluntary consumption of alcohol or drugs, by itself, is not a mental disease or defect. Where a defendant lacks substantial capacity to appreciate the wrongfulness of his conduct or to conform his conduct to the law solely as a result of voluntary intoxication, then he is criminally responsible for his conduct. However, the consumption of alcohol or drugs may trigger or intensify (make worse) a defendant’s preexisting mental disease or defect. If it does so, and the mental disease or defect then causes the defendant to lose the substantial capacity to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law, the defendant is not criminally responsible for his conduct. There is one exception to the principle just stated. A defendant who loses the substantial capacity … after he consumes drugs or alcohol, who knows or had reason to know that consumption would trigger or intensify in him a mental illness or condition that could cause him to lack that capacity, is criminally responsible for his resulting conduct. In deciding what the defendant had reason to know about the consequences of his consumption of drugs or alcohol, you should consider the question solely from the defendant’s point of view, including his mental capacity and his past experience with drugs or alcohol. But you must keep in mind that . . . where a defendant, at the time the crime is committed, has a mental disease or defect that itself causes him to lack the substantial capacity …he is not criminally responsible for his conduct regardless of whether he uses or does not use alcohol or drugs. That is true even if he does use alcohol or drugs and the alcohol or drug use makes the symptoms of his mental disease or defect worse, and even if he knew they would make his symptoms worse.”

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