Can Mental Health Affect Criminal Responsibility in Massachusetts? Understanding the Lack of Criminal Responsibility Defense
When someone is charged with a serious crime and has a significant history of mental illness, one of the first questions families often ask is whether the person’s mental health can affect whether they are held criminally responsible.
In Massachusetts, the answer is yes — under specific and carefully defined circumstances. The law recognizes that certain mental diseases or defects can prevent a person from understanding the wrongfulness of their conduct or from controlling their behavior in accordance with the law. When that happens, the person may be found not criminally responsible.
This defense is commonly known outside the courtroom as the “insanity defense.” Inside Massachusetts courts, lawyers and judges prefer the more precise term lack of criminal responsibility.
What Is Lack of Criminal Responsibility?
Under Massachusetts law, a person is not criminally responsible for their conduct if, at the time of the offense, they had a mental disease or defect that caused them either:
- To lack the substantial capacity to appreciate the wrongfulness (or criminality) of their conduct, or
- To lack the substantial capacity to conform their conduct to the requirements of the law.
This standard combines elements of both the traditional M’Naghten rule (understanding right from wrong) and the concept of irresistible impulse (ability to control one’s behavior). Importantly, the law does not require a specific medical diagnosis. The question is whether the defendant suffered from a mental disease or defect that substantially impaired one of those two capacities at the time of the alleged crime.
Does the Person Need a Significant Mental Illness?
Yes. The person must have a mental disease or defect. This is a legal term, not a medical one. It does not require a formal DSM diagnosis, but the condition must be serious enough that it substantially impairs the person’s ability to appreciate the wrongfulness of their conduct or to control their behavior.
Conditions that more commonly support a lack-of-criminal-responsibility defense include:
- Severe psychotic disorders (for example, schizophrenia or schizoaffective disorder) involving active delusions or hallucinations
- Bipolar disorder with psychotic features during a manic or mixed episode
- Certain severe organic brain disorders or traumatic brain injuries that significantly impair reality testing or impulse control
- Profound intellectual disability in some cases
Conditions that rarely qualify on their own include:
- Ordinary depression or anxiety
- PTSD (unless it produces psychotic-level symptoms)
- Personality disorders
- Ordinary emotional distress, anger, or poor judgment
“Insanity Defense” vs. “Lack of Criminal Responsibility”
In popular culture, people almost always refer to the “insanity defense.” Massachusetts courts and lawyers deliberately avoid that phrase. The preferred term is lack of criminal responsibility because it more accurately describes the legal inquiry and reduces the risk of confusing jurors with medical or sensationalized ideas of “insanity.” When the issue is properly raised, the jury is instructed on lack of criminal responsibility rather than on a medical definition of insanity.
How the Issue Is Raised and Who Has the Burden of Proof
Massachusetts law starts with a presumption that every person is sane and criminally responsible. The defense must introduce some evidence that raises a reasonable question about the defendant’s mental state at the time of the offense.
Once the issue is properly raised, the burden shifts. The Commonwealth must then prove beyond a reasonable doubt that the defendant was criminally responsible. In other words, the prosecution must prove either that the defendant did not suffer from a mental disease or defect, or that even if the defendant did have a mental disease or defect, they still retained the substantial capacity both to appreciate the wrongfulness of their conduct and to conform their conduct to the law.
This burden-shifting rule is significant. Many people assume the defense must “prove” insanity. In Massachusetts, once the issue is legitimately raised, it is the Commonwealth that must disprove it beyond a reasonable doubt. For more on the concept of reasonable doubt, see our related post.
The Role of Mental Health Experts
In almost every serious case involving a claim of lack of criminal responsibility, the defense retains a qualified forensic mental health expert (typically a psychiatrist or psychologist). That expert evaluates the defendant, reviews records, and prepares a written report.
If the report is favorable to the defense, a copy is typically provided to the Commonwealth. The prosecution then reviews the report and decides whether to hire its own expert. In most cases, the Commonwealth does retain a competing expert.
When the Commonwealth chooses not to hire its own expert, that is a significant advantage for the defense. At trial — whether before a judge or a jury — the defense expert’s opinions will face no opposing expert testimony. That can make the lack-of-criminal-responsibility claim considerably stronger.
For more on the use of experts in criminal cases, see Do I Need an Expert Witness?.
What Happens If a Person Is Found Not Criminally Responsible?
A finding of not guilty by reason of lack of criminal responsibility does not mean the person is simply released.
After such a verdict, the court almost always orders a period of evaluation and possible commitment. In many cases the person is sent to Bridgewater State Hospital or another secure psychiatric facility for evaluation. The initial period is often six months, after which the facility may petition the court for further commitment if the person remains mentally ill and presents a danger to themselves or others. The focus shifts from punishment to treatment and public safety. The length of commitment is not tied to the maximum sentence for the original charge; it is governed by the person’s ongoing mental condition and dangerousness.
Voluntary Intoxication and Mental Illness
Voluntary intoxication by alcohol or drugs, by itself, does not constitute a mental disease or defect for purposes of the lack-of-criminal-responsibility defense. A person who commits a crime solely because they were drunk or high remains criminally responsible.
There is a limited exception. If the defendant already suffered from a mental disease or defect, and the voluntary use of substances aggravated that condition to the point that the legal standard is met, the defense may still be available. However, if the person knew or should have known that using substances would trigger or worsen their condition, the defense is often unavailable.
Competency to Stand Trial vs. Criminal Responsibility
These two concepts are frequently confused but address entirely different questions:
- Competency focuses on the present. It asks whether the defendant can currently understand the court proceedings and assist in their own defense.
- Criminal responsibility focuses on the past. It asks about the defendant’s mental state at the time of the alleged crime.
A person can be competent to stand trial today and still have lacked criminal responsibility at the time of the alleged offense. The reverse is also possible.
Mental Impairment Short of Lack of Criminal Responsibility
Even when a full lack-of-criminal-responsibility defense is not available, evidence of mental illness or impairment can still be relevant. Massachusetts law permits the jury to consider mental impairment that falls short of the full defense when deciding whether the Commonwealth has proved specific intent or knowledge elements of a crime. This is sometimes discussed under the heading of mental impairment short of insanity.
Related concepts of criminal intent and transferred intent can also become important in these cases.
Practical Considerations for Defendants and Families
Raising lack of criminal responsibility is a major strategic decision. It usually requires:
- Early retention of a qualified forensic mental health expert
- Careful collection and preservation of medical and psychiatric records
- Thoughtful timing of disclosures to the Commonwealth
- Realistic assessment of the strength of the clinical evidence
- Consideration of the consequences of a successful claim (hospitalization rather than prison)
Because the stakes are high and the legal and clinical issues are complex, experienced criminal defense counsel is essential.
Frequently Asked Questions
Is the insanity defense easy to win in Massachusetts?
No. Successful claims are relatively uncommon. The legal standard is high, and juries are often skeptical.
Does a successful claim mean the person goes free?
No. The person is typically hospitalized for evaluation and possible long-term commitment based on ongoing mental illness and dangerousness.
Can depression or anxiety alone support the defense?
Almost never. The condition must substantially impair the ability to understand wrongfulness or control behavior.
Who decides the issue — the judge or the jury?
In a jury trial, the jury decides whether the Commonwealth has proved criminal responsibility beyond a reasonable doubt.
Questions About Mental Health and Criminal Charges?
IF YOU OR A LOVED ONE HAVE BEEN CHARGED WITH A CRIME, AND YOU NEED AN EXPERIENCED CRIMINAL DEFENSE LAWYER WORKING ON YOUR SIDE TO PROTECT YOUR RIGHTS, PLEASE CONTACT CRIMINAL DEFENSE ATTORNEY WILLIAM J. BARABINO.
CALL 781-393-5900 TO LEARN MORE ABOUT YOUR AVAILABLE DEFENSES.
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