Understanding the Massachusetts Lack of Criminal Responsibility Defense, the Commonwealth's Burden of Proof, and What a Not Criminally Responsible Verdict Actually Means
By Patrick L. Garrity, Boston Criminal Defense Attorney
The Lindsay Clancy murder trial has now reached the stage that ultimately matters most: jury deliberations.
After weeks of testimony in Plymouth Superior Court concerning Clancy's mental health, psychiatric treatment, medications, conduct before and after the deaths of her three children, and competing expert opinions, the case has been submitted to the jury.
The central legal question has been discussed publicly as whether Lindsay Clancy was “insane” when she killed her children.
That is not quite how Massachusetts law frames the issue.
Massachusetts uses the term lack of criminal responsibility, often abbreviated as LCR.
And understanding that distinction is important because the jury is not being asked simply whether Lindsay Clancy suffered from postpartum depression, postpartum psychosis, bipolar disorder, or another psychiatric condition.
The ultimate question is a legal one:
Has the Commonwealth proved beyond a reasonable doubt that Lindsay Clancy was criminally responsible for her conduct at the time of the killings?
As a Massachusetts criminal defense attorney who regularly handles serious Superior Court cases, I think the Clancy trial provides an unusually visible example of how different a criminal-responsibility case is from the way an “insanity defense” is often portrayed publicly.
I am not involved in the Lindsay Clancy case and offer no opinion about what verdict this jury should return. But the legal framework the jurors must apply is worth understanding.
What Is Lindsay Clancy Charged With?
Lindsay Clancy was charged in Plymouth Superior Court with three counts of first-degree murder arising from the January 2023 deaths of her three children, Cora, Dawson, and Callan Clancy.
The central factual question at trial has not been whether Clancy caused their deaths.
Her defense has instead centered on whether she was criminally responsible when she did so.
The defense has argued that Clancy was suffering from postpartum psychosis and severe mental illness. The Commonwealth has presented its own psychiatric evidence and has argued that her conduct demonstrated planning, awareness, and an understanding that what she was doing was wrong.
After approximately five weeks of testimony, both sides delivered closing arguments on August 27, 2026, and the case went to the jury.
That means the highly publicized medical testimony ultimately has to be translated into a very specific Massachusetts legal test.
Massachusetts Does Not Technically Use an “Insanity Defense”
Most people searching for information about the Lindsay Clancy case will understandably use the phrase insanity defense.
Lawyers and judges in Massachusetts generally use different terminology.
The defense is called lack of criminal responsibility.
The Massachusetts Supreme Judicial Court's current Model Jury Instructions on Homicide provide the governing framework:
A person is not criminally responsible if that person has a mental disease or defect and, because of that mental disease or defect, lacks the substantial capacity either:
- to appreciate the criminality or wrongfulness of the conduct; or
- to conform the conduct to the requirements of the law.
Importantly, Massachusetts also instructs juries that “mental disease or defect” is a legal term rather than simply a medical diagnosis.
That distinction is critical.
A diagnosis by itself does not resolve the case.
Having a Mental Illness Does Not Automatically Mean Someone Lacks Criminal Responsibility
This may be the most important misconception surrounding cases like Lindsay Clancy's.
A defendant can suffer from serious mental illness and still be criminally responsible under Massachusetts law.
The legal question is not simply:
Was Lindsay Clancy mentally ill?
It is:
Did a mental disease or defect deprive her of the substantial capacity to appreciate that her conduct was criminal or wrong, or deprive her of the substantial capacity to conform her conduct to the requirements of law?
Those are very different questions.
A psychiatric diagnosis is evidence.
Symptoms are evidence.
Medical records are evidence.
Statements made before and after the alleged crime are evidence.
Expert opinions are evidence.
But ultimately the jury applies the legal standard.
That is one reason these trials can become so complicated.
Who Has the Burden of Proof?
This is another area where the phrase “insanity defense” can be misleading.
Once lack of criminal responsibility is properly at issue in a Massachusetts criminal case, the defendant does not bear the ultimate burden of proving insanity.
The Commonwealth must prove criminal responsibility beyond a reasonable doubt.
The Massachusetts homicide instructions state this directly:
The Commonwealth must prove both that the defendant committed the offense and that the defendant was criminally responsible for the conduct. The defendant does not carry the burden of proving lack of criminal responsibility.
That is a significant feature of Massachusetts law.
In practical terms, once the issue is fairly raised, criminal responsibility becomes something the prosecution must establish as part of its case.
What Exactly Does the Commonwealth Have to Prove?
Massachusetts law gives the Commonwealth different ways to prove criminal responsibility.
Most relevant to the public discussion in the Clancy case, the Commonwealth can attempt to prove beyond a reasonable doubt that, even if the defendant suffered from a mental disease or defect, she nevertheless retained the substantial capacity both to:
- appreciate the criminality or wrongfulness of her actions; and
- conform her conduct to the requirements of the law.
The current Massachusetts model instructions explain that appreciating wrongfulness means understanding in some meaningful way that the conduct was illegal or wrong.
That is why so much of a criminal-responsibility trial can focus on behavior surrounding the crime.
Why Does the Prosecution Focus So Much on Planning?
Public coverage of the Lindsay Clancy trial has repeatedly discussed evidence the prosecution characterizes as showing deliberation or planning.
The Commonwealth has emphasized circumstances surrounding the killings, including Clancy's conduct before her husband left the house and what prosecutors argue was an effort to create an opportunity to be alone with the children. The defense disputes the prosecution's interpretation and argues that her actions occurred in the context of severe psychiatric illness.
Why is evidence like that legally relevant?
Because Massachusetts law permits the Commonwealth to rely not only on psychiatric experts but also on the circumstances of the offense and the defendant's words and actions in attempting to prove criminal responsibility.
Massachusetts evidence law expressly recognizes that expert testimony is not the only way criminal responsibility may be established. The Commonwealth may rely upon the defendant's conduct surrounding the offense.
That does not mean planning automatically proves criminal responsibility.
It means it is evidence the jury can consider.
Why Does the Defense Focus So Heavily on Postpartum Psychosis?
The defense theory is essentially the opposite.
The defense has presented evidence that Clancy suffered from severe postpartum mental-health problems, including what its experts characterize as postpartum psychosis, and that her mental state deteriorated despite repeated attempts to obtain psychiatric care.
Defense witnesses have testified about her psychiatric symptoms, medications, treatment history, and mental condition around the time of the killings.
From a criminal-responsibility perspective, however, the diagnosis is only the starting point.
The defense theory must connect the alleged mental disease or defect to capacity at the time of the offense.
That is what makes the timing so important.
The Jury Is Evaluating Lindsay Clancy's Mental State at the Time of the Killings
A criminal-responsibility defense is ultimately temporal.
A defendant may have been seriously ill before the offense.
The defendant may be seriously ill afterward.
The defendant may require extensive treatment today.
But the legal question focuses on the defendant's mental capacity when the charged conduct occurred.
This can force lawyers and experts to reconstruct someone's mental state retrospectively.
In a case involving psychiatric illness, that may require the jury to evaluate:
- treatment records;
- medication history;
- contemporaneous text messages;
- communications with family;
- communications with medical professionals;
- journal entries;
- observations from friends and family;
- statements made after the offense;
- behavior immediately before and after the offense;
- expert psychiatric opinions;
- competing diagnoses;
- and inconsistencies in different accounts.
The Lindsay Clancy trial has featured many of these categories of evidence.
That is not unusual in a serious criminal-responsibility case.
Why Can Experts Reach Completely Different Conclusions?
The Clancy trial has featured competing mental-health experts who reached sharply different conclusions about her psychiatric state and criminal responsibility.
That may seem strange to people outside the criminal court system.
It should not.
Forensic psychiatric analysis is not simply a laboratory test where both experts enter the same data and necessarily receive the same numerical answer.
Experts may disagree about:
- diagnosis;
- reliability of reported symptoms;
- when symptoms developed;
- significance of medications;
- credibility of statements;
- whether a claimed hallucination is clinically consistent;
- whether particular behavior demonstrates organization or psychosis;
- and ultimately whether a psychiatric condition affected one of the legally relevant capacities.
The defense presented experts supporting its theory of psychosis and lack of criminal responsibility. The Commonwealth responded with experts who concluded that Clancy remained criminally responsible.
The jury is not required to accept an expert's conclusion simply because the witness has impressive credentials.
Jurors ultimately determine what testimony they find credible and how the evidence fits together.
Can the Prosecution Have Its Own Psychiatrist Evaluate the Defendant?
Yes.
This is an important part of Massachusetts criminal-responsibility practice that sometimes surprises defendants.
When a defendant affirmatively places criminal responsibility at issue and intends to rely upon expert psychiatric evidence, the Commonwealth is not required simply to accept the defense experts' conclusions.
The prosecution is permitted to obtain its own expert evaluation and, in a case where criminal responsibility is genuinely contested, will ordinarily do so.
The Lindsay Clancy trial demonstrates exactly why.
The jury heard sharply different expert opinions concerning her mental condition and whether she remained capable of understanding and controlling her conduct.
A serious LCR defense therefore cannot be prepared on the assumption that the defense expert's opinion will go unanswered.
Does the Jury Have to Choose Which Psychiatrist It “Believes”?
Not exactly.
Expert credibility is obviously important, but jurors are evaluating the entire body of evidence.
A juror could agree with an expert's diagnosis but disagree with the expert's ultimate conclusion about criminal responsibility.
A juror could question one part of an expert's analysis but credit another.
A juror could place substantial weight on contemporaneous records rather than retrospective statements.
Or a juror might believe the psychiatric evidence is strong enough, when considered with the remaining evidence, to create reasonable doubt about criminal responsibility.
This is why reducing a criminal-responsibility trial to a contest between psychiatrists misses much of what the jury actually does.
The Commonwealth Must Prove Criminal Responsibility Beyond a Reasonable Doubt
This bears repeating because it changes how the evidence is evaluated.
The question is not whether jurors think it is more likely than not that Lindsay Clancy was criminally responsible.
That would be a civil standard.
The Commonwealth carries the criminal burden of proof.
If lack of criminal responsibility has been properly raised, the Massachusetts jury instructions require the prosecution to establish criminal responsibility beyond a reasonable doubt.
That means uncertainty about psychiatric evidence can have legal significance.
But it does not mean that any disagreement among doctors automatically produces an LCR verdict.
Jurors must assess the evidence as a whole under the judge's instructions.
What Happens If the Jury Finds Lindsay Clancy Criminally Responsible?
If the jury concludes that the Commonwealth has proved criminal responsibility beyond a reasonable doubt, it then evaluates the homicide charges under the court's remaining instructions.
The jury in the Clancy case has been instructed on first-degree murder and lesser homicide alternatives, including second-degree murder and manslaughter.
The exact verdict therefore depends on which elements, if any, the Commonwealth proves beyond a reasonable doubt.
A first-degree murder conviction carries life imprisonment without the possibility of parole under Massachusetts law.
What Happens If Lindsay Clancy Is Found Not Guilty by Reason of Lack of Criminal Responsibility?
A widespread misconception is that an LCR verdict means:
The defendant simply goes home.
That is not how Massachusetts law works.
Massachusetts model jury instructions explain that following a verdict of not guilty by reason of lack of criminal responsibility, the district attorney or another appropriate authority may, and generally does, seek the defendant's commitment to a mental-health facility.
If the court determines that the person remains mentally ill and that release would create a substantial likelihood of serious harm, the court can order commitment.
Those commitment orders can continue to be renewed.
There is no fixed maximum number of renewals so long as the legal requirements for continued commitment remain satisfied. In appropriate circumstances, an individual could remain hospitalized for life.
So “not guilty by reason of lack of criminal responsibility” does not mean “nothing happens.”
It means the legal system responds through a mental-health commitment framework rather than a criminal sentence.
Is a Lack of Criminal Responsibility Verdict the Same as an Ordinary Acquittal?
No, not in its practical consequences.
A conventional not-guilty verdict generally ends the criminal prosecution and the defendant is not subjected to punishment for the charged offense.
An LCR verdict likewise means that the Commonwealth has failed to establish criminal responsibility.
But Massachusetts law then provides a specific framework for evaluation and potential civil commitment because of the mental-health condition underlying the verdict.
Under G.L. c. 123, § 16, the court may order observation and examination, and appropriate authorities may petition for commitment. Additional commitment periods may follow if the statutory requirements remain satisfied.
That is why the consequences of an LCR verdict should neither be described as ordinary incarceration nor as simply “walking free.”
Why the Lindsay Clancy Case Is Legally Different From Many Other High-Profile Murder Trials
Most homicide trials focus heavily on identity and intent.
Did the defendant kill the victim?
Was the killing intentional?
Was it premeditated?
Was there adequate provocation?
Was it self-defense?
In the Clancy case, the defense has acknowledged that she caused the children's deaths.
The dispute therefore shifts dramatically.
The jury has been asked to evaluate not simply what happened, but the legal significance of Clancy's mental condition when it happened.
That fundamentally changes trial preparation.
Medical records that might be peripheral in another homicide case can become central evidence.
Psychiatrists become critical witnesses.
Medication history may become contested.
Statements to clinicians can take on enormous significance.
The defendant's behavior weeks or months before the crime may be examined alongside what happened during a matter of minutes.
And ordinary conduct can become contested evidence from which each side asks the jury to draw very different conclusions.
Criminal Responsibility Is a Legal Question, Not a Medical Diagnosis
If there is one point people should take from the Lindsay Clancy trial, it is this:
Postpartum psychosis and lack of criminal responsibility are not synonymous.
One is a medical concept.
The other is a legal conclusion.
A psychiatrist can diagnose a mental illness.
The psychiatrist can offer opinions about symptoms and capacity.
But ultimately, the jury determines criminal responsibility under Massachusetts law.
That division between medicine and law explains much of the disagreement visible in the Clancy trial.
What Makes an LCR Defense So Difficult?
In my view, one of the greatest challenges in litigating criminal responsibility is translating psychiatric evidence into ordinary human behavior that twelve jurors can evaluate.
Terms like:
- psychosis;
- delusion;
- command hallucination;
- major depressive episode;
- bipolar disorder;
- intrusive thoughts;
- dissociation; and
- substantial capacity
have specific clinical or legal meanings.
Jurors then have to apply those concepts to conduct that may look organized in one context and profoundly disordered in another.
The prosecution will often focus on behavior suggesting awareness, concealment, planning, or avoidance of detection.
The defense may focus on evidence showing deterioration, delusion, impaired perception, irrational thinking, treatment history, or behavior inconsistent with ordinary motive.
Neither side wins simply by attaching a diagnostic label to the defendant.
The difficult work is establishing what that condition meant at the moment of the crime.
Why Massachusetts Makes Criminal Responsibility a Question for the Commonwealth
The burden of proof reflects one of the most fundamental principles of our criminal system.
The Commonwealth must prove the components necessary to impose criminal punishment.
Once there is sufficient evidence placing criminal responsibility genuinely in dispute, Massachusetts does not require the defendant to establish lack of responsibility beyond a reasonable doubt.
The Commonwealth must establish criminal responsibility.
That distinction can become outcome-determinative in a close case.
What Should People Watch for in the Lindsay Clancy Verdict?
As the jury deliberates, the eventual verdict may tell us the jury's ultimate conclusion.
It ordinarily will not tell us precisely how each juror weighed every psychiatric opinion, medical record, statement, and disputed piece of evidence.
Jurors generally do not issue written opinions explaining their reasoning.
Whatever result is returned, it should therefore be approached carefully.
A guilty verdict would not mean that postpartum psychosis does not exist.
An LCR verdict would not mean that every person diagnosed with postpartum psychosis is legally excused from criminal conduct.
The verdict will mean that this jury applied Massachusetts law to the particular evidence presented concerning Lindsay Clancy.
That is all.
What the Lindsay Clancy Trial Teaches About Massachusetts Criminal Defense
Highly publicized criminal cases often produce simple public narratives.
The courtroom is rarely that simple.
The Lindsay Clancy case has required jurors to evaluate homicide law, psychiatric medicine, conflicting expert testimony, medical treatment, medications, contemporaneous conduct, statements, and the Commonwealth's burden of proof.
Cases involving mental health can therefore require a defense team to operate simultaneously in two different worlds:
medicine and law.
The strongest legal argument means little if counsel does not understand the medical evidence.
And the strongest psychiatric diagnosis does not itself answer the legal question the jury must decide.
That intersection is what makes lack-of-criminal-responsibility litigation among the most complicated forms of Massachusetts criminal defense.
About Patrick L. Garrity
Patrick L. Garrity is a Boston criminal defense attorney at Brad Bailey Law, P.C. who represents individuals facing serious Massachusetts state and federal criminal charges.
His practice includes Massachusetts Superior Court jury trials, serious felony and sex-crime defense, homicide-related matters, federal criminal defense, expert and forensic evidence, constitutional litigation, and complex criminal investigations.
Patrick has served as counsel in numerous Massachusetts Superior Court and federal jury trials and regularly works with expert witnesses, extensive medical and digital records, evidentiary motions, witness preparation, and other issues that arise in serious criminal prosecutions.
He also writes about developments in Massachusetts criminal law and high-profile criminal cases to explain the legal rules that are often lost in public coverage.
Patrick Garrity is not counsel in the Lindsay Clancy case. This article discusses publicly reported proceedings and Massachusetts law and does not express an opinion concerning the appropriate verdict.
Prior results do not guarantee a similar outcome.