Can Mental Illness Be a Defense to a Criminal Charge in Massachusetts?

Most families who call us about this are carrying two fears at once. They are frightened about the charge, and they are frightened for their loved one, who may have been struggling for a long time before law enforcement got involved. Many have watched someone they love get worse and could not get them help. If that is where you are, you are not alone, and you are not wrong to ask whether the illness matters.

It does matter. But the way it matters in a Massachusetts courtroom is often different from what people expect. If you are reading this for a son, a daughter, a spouse, or a parent, the first conversation with us is free for you, just as it is for the person charged.

Key Information: What You Need to Know

Two different things. Mental illness can matter in a criminal case in two very different ways. One is a defense at trial: a verdict of not guilty by reason of lack of criminal responsibility, which is what most people mean by the insanity defense. The other is mitigation: a person's mental health shaping how the case is resolved and what sentence is imposed. This post covers the defense first, and then mitigation.

The standard for the defense is high and strict. Having a mental illness, even a severe one, is not enough on its own. The question is whether, at the time of the offense, the illness took away the person's substantial capacity to understand that what they were doing was wrong or to control their conduct.

The person charged does not have to prove anything. Once the issue is raised, the Commonwealth must prove beyond a reasonable doubt that the person was criminally responsible.

Raising it sets things in motion. The defense must give written notice, the court can order an examination by the Commonwealth's expert, and the defense must turn over the mental health records it holds. These are decisions to make carefully, with a lawyer, before anything is filed.

A successful defense does not mean going home. After that verdict, the court can order a hospital stay for observation, and the person can be committed to a psychiatric hospital for as long as they remain mentally ill and dangerous.

Mitigation is a separate question, and it often matters more. Even when the defense does not apply, a person's mental health can matter a great deal. In our experience, it is often most important in negotiating the case and at sentencing.

What "Lack of Criminal Responsibility" Means

People usually call this the insanity defense. Massachusetts law calls it lack of criminal responsibility, and the verdict is "not guilty by reason of lack of criminal responsibility."

The test comes from the Supreme Judicial Court's decision in Commonwealth v. McHoul. A person is not criminally responsible if, at the time of the conduct, as a result of a mental disease or defect, they lacked substantial capacity either to appreciate the wrongfulness of their conduct or to conform their conduct to the requirements of the law.

That is not the old "right from wrong" test that some websites still describe. Massachusetts law has two parts, and either one is enough. A person can know, in an intellectual sense, that something is wrong and still lack the capacity to control what they do because of their illness.

Three points about the wording matter:

• "Mental disease or defect" is a legal term, not a medical one. It does not have to fit a formal diagnosis. It does not include a condition that shows itself only through repeated criminal or antisocial behavior.
• "Substantial" capacity. The question is not whether the person had some trouble thinking clearly. It is whether the illness took away their substantial capacity to understand or to control what they did.
• At the time of the offense. What matters is the person's condition when the conduct happened, not before and not after.

Who Has to Prove It

In Massachusetts, the person charged never has to prove a lack of criminal responsibility. The model jury instruction used in the District Court says so directly. Once the issue is in the case, the Commonwealth must prove beyond a reasonable doubt both that the person committed the offense and that they were criminally responsible when they did it.

The Commonwealth can meet that burden in either of two ways. It can prove that the person did not have a mental disease or defect at the time. Or it can prove that, even if the person did, they still had the substantial capacity to appreciate the wrongfulness of their conduct and to conform it to the law.

That second route is why this defense is so hard to win. Prosecutors do not have to prove that the person was well. They only have to prove that the illness did not take away the capacities that matter. The notes to the model instruction explain that the Commonwealth does not even need its own expert. It can rely on the circumstances: planning, a rational motive, rational choices while committing the offense or avoiding capture, efforts to hide it, and what the person said and did before, during, and after. Judges and juries tend to look hard at that kind of evidence.

What Raising the Defense Sets in Motion

This is not a decision to make lightly, and it is not one a family should make alone. Under Rule 14.4 of the Massachusetts Rules of Criminal Procedure, here is what follows:

• Written notice. If the defense intends to raise the person's mental condition at trial, or to offer expert testimony about it, it must notify the prosecutor in writing, generally by the deadline for pretrial motions. The notice names the defense experts and says whether they will rely on the person's own statements.
• An examination by the Commonwealth's expert. If a defense expert will rely on what the person has said about their mental condition, the judge can order the person to be examined by an examiner for the Commonwealth.
• Records go to that examiner. Within 14 days after the examiner is designated, the defense must give the examiner all of the person's mental health and medical records that defense counsel has, along with the raw data from any testing the defense expert did. That duty continues as new records come in.
• Some protection for what is said. What the person says during the court-ordered examination cannot be revealed to the prosecution unless the judge orders it, and the examiner's report stays sealed until certain conditions are met.
• Refusing has consequences. If the person refuses a court-ordered examination, the judge can exclude the defense expert's testimony or allow evidence of the refusal.

In practice, raising this defense usually means not contesting that the person did what is charged. The defense becomes about why it happened and what the person's mind was capable of at the time. That is a serious strategic choice. It should be made only after the evidence, the records, and the expert opinions have been reviewed, and only with the person's full participation.

A related but different question is whether someone is well enough right now to understand the case and work with a lawyer. That is called competency, and we explain it in our post on mental health issues in a criminal case.

When Drugs or Alcohol Are Part of the Picture

Many people living with mental illness also use alcohol or drugs, sometimes to quiet symptoms nobody was treating. The law treats this carefully, and the District Court's model instruction sets out the rules:

• Intoxication from voluntarily using alcohol or drugs is not, by itself, a mental disease or defect. If intoxication alone is what took away the person's capacity, they are criminally responsible.
• But alcohol or drugs can trigger or worsen an illness the person already had. If that happens, and the illness then takes away the person's substantial capacity, they are not criminally responsible.
• There is an exception. If the person knew or had reason to know that drinking or using would trigger or worsen their illness in that way, they can be held responsible. That question is judged from the person's own point of view, including their mental capacity and past experience.
• If the illness by itself took away the person's capacity, they are not criminally responsible, whether or not they also used alcohol or drugs, and even if the substances made the symptoms worse.

These cases turn on history: what the person knew about their own illness, what treatment they had or did not have, and what had happened before. That history has to be gathered early and carefully.

When It Is Not Insanity, but Still Matters

Some charges require proof that the person acted with a specific intent, for example, an intent to cause a particular result. For those charges, the District Court's model instructions allow the jury to consider evidence of a mental impairment that falls short of a lack of criminal responsibility when deciding whether the Commonwealth has proved that intent.

This is not an excuse for the conduct. A person who could and did form the required intent can still be convicted. But a person whose condition meant they could not form it must be acquitted of that charge.

What Happens After a Not Guilty by Reason of Lack of Criminal Responsibility Verdict

Families are often surprised by this part. A verdict of not guilty by reason of lack of criminal responsibility does not mean the person walks out of the courtroom free. Under G.L. c. 123, § 16:

• The court may order the person hospitalized for up to 40 days for observation and examination. In some cases that can be at Bridgewater State Hospital.
• During that period, or within 60 days after the verdict, the prosecutor or hospital officials may ask the court to commit the person to a psychiatric facility or to Bridgewater State Hospital. A first commitment order lasts six months.
• After that, the person can be committed for additional one-year periods. The model jury instruction explains that this can continue for as long as the person remains mentally ill and dangerous, which can mean for life.
• The prosecutor must be notified of these hearings and has the right to be heard. The decision on whether to continue the commitment or release the person is made by the court.

Juries in these cases are entitled to be told this, so that they understand a not-responsible verdict is not a way out of consequences.

Mitigation: How Mental Health Usually Matters Instead

We want to be honest with you. This defense is extremely challenging, and it applies to a small number of actual cases. The standard is high and strict, and the mere presence of mental illness, even severe illness, is not enough.

That does not mean mental illness is beside the point. In our experience, it is often most important in two places.

Negotiating the case. A well-documented history, an evaluation from a qualified professional, and a person who is in treatment can change how a prosecutor sees a case. It can open the door to outcomes built around treatment and supervision rather than punishment alone. Our post on getting mental health treatment while a case is open explains how that works and what to watch out for.

Sentencing. When a case does end in a conviction, a person's mental health, trauma, and history can be central to what the judge decides. That has to be prepared well before the sentencing date. We explain how in our post on trauma and sentencing.

We work with a network of evaluators and treatment providers so that the right professional can be brought in at the right time. And we never promise an outcome. A lawyer who promises you one in a case like this should be distrusted.

To see how a case moves from the first court date to the end, read our guide to the Massachusetts criminal court process.

Frequently Asked Questions

Q: If my family member has a serious diagnosis, does that mean they are not responsible?

A: No. A diagnosis, even a severe one, is not enough by itself. The question is whether the illness took away the person's substantial capacity to appreciate that their conduct was wrong or to control it, at the time it happened. The Commonwealth can prove responsibility by showing the person kept those capacities despite the illness.

Q: Does the person charged have to prove they were not responsible?

A: No. Once the issue is raised, the Commonwealth must prove criminal responsibility beyond a reasonable doubt. There is no burden on the person charged.

Q: Will their mental health records be turned over?

A: If the defense raises the person's mental condition and the court orders an examination by the Commonwealth's examiner, the defense must give that examiner the mental health and medical records it holds. That is one reason this decision should be made with a lawyer, carefully, before anything is filed.

Q: If they are found not responsible, do they go home?

A: Not necessarily. The court can order up to 40 days of hospitalization for observation, and the person can then be committed for as long as they remain mentally ill and dangerous, with court review at set intervals.

Q: They had been drinking or using. Does that rule out this defense?

A: Not automatically. Intoxication alone is not a mental disease or defect. But if alcohol or drugs triggered or worsened an illness the person already had, the defense may still apply, unless the person knew or had reason to know that would happen. These cases depend heavily on the person's history.

Q: If this defense will not work, does their mental health still matter?

A: Yes. In our experience it is often most important in negotiating the case and at sentencing, where a documented history, a qualified evaluation, and treatment can make a real difference.

Contact Ernest Stone Today

If someone you love has been charged and mental illness is part of the story, you do not have to figure this out alone. The decisions made early in a case like this matter, and some of them are hard to undo.

Call 978-969-2890 for a free consultation with a Massachusetts criminal defense attorney. If you are calling about someone in your family, that consultation is free too.

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We represent good people who had a really bad day.

H. Ernest Stone, Attorney PC

900 Cummings Center, Suite 321-U

Beverly, MA 01915

Phone: (978) 969-2890

Email: es@herneststone.com

We'll Get You Through the Storm

Criminal charges can feel overwhelming, and when mental illness is part of the picture, the whole family feels it. You don't have to face it alone. With more than 30 years of experience defending clients throughout Massachusetts, we know how to navigate the system and protect your rights. Every case is different, and we'll build a defense around yours.