Published July 21, 2026
Jury selection began yesterday in Plymouth Superior Court in Commonwealth v. Lindsay Clancy, before Judge William Sullivan. Clancy, a former labor and delivery nurse, is charged with three counts of first degree murder in the January 24, 2023 deaths of her children, Cora, age five, Dawson, age three, and Callan, eight months, at the family’s home in Duxbury. She has pleaded not guilty and is presumed innocent. Prosecutors dropped three strangulation counts on July 9 as redundant of the murder charges, so the jury eventually seated will decide the murder counts alone.
This will not be a whodunit. The defense has acknowledged that Clancy caused her children’s deaths and will argue that she was not criminally responsible because she was in the grip of a severe psychiatric illness, with postpartum psychosis at the center of that claim. The Commonwealth will argue that she acted with deliberate premeditation despite her mental health treatment. Once testimony begins, the coverage will focus on the emotional weight of the evidence. The legal questions the jurors must actually answer are narrower, and more technical, than most of that coverage will suggest. This article walks through them.
Competent to stand trial is not the same as criminally responsible
Start with a distinction that confuses even careful observers. Clancy has already been evaluated and found competent to stand trial. That finding answers only a present tense question: does she now have the capacity to understand the proceedings and assist her lawyers in a rational way. It says nothing about her mental state on January 24, 2023.
Criminal responsibility, by contrast, is a past tense question. It asks about the defendant’s mind at the moment of the conduct charged. A person can be fully competent today and still have lacked criminal responsibility years ago, and the reverse is equally true. The competency finding cleared the way for trial. It resolved nothing that the jury will decide.
The McHoul standard
Massachusetts defines lack of criminal responsibility through Commonwealth v. McHoul, 352 Mass. 544 (1967), where the Supreme Judicial Court adopted the American Law Institute’s Model Penal Code formulation. The operative language, quoted in McHoul from Section 4.01 of the Code, reads:
“A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law.”
Three features of this test matter for the Clancy trial. First, it is disjunctive. The defense prevails on the responsibility question if the jury finds either prong satisfied: an inability to appreciate wrongfulness, or an inability to conform conduct to law. A defendant who understood on some level that her acts were wrong may still lack criminal responsibility if mental disease deprived her of the capacity to control her conduct. That second prong, sometimes called the volitional prong, is one many other states abandoned decades ago. Massachusetts kept it.
Second, the test requires only a lack of “substantial capacity,” not total incapacity. Jurors are not asked whether Clancy had any awareness at all, but whether mental disease or defect left her without substantial capacity in either respect.
Third, everything runs through the phrase “as a result of mental disease or defect.” A diagnosis alone does not establish lack of responsibility. The jury must connect the illness to the incapacity, at the time of the killings, not weeks before or after.
The burden of proof: the feature that makes Massachusetts unusual
Here is the piece of Massachusetts law that national commentary on this case most often gets wrong. In most American jurisdictions, insanity is an affirmative defense that the defendant must prove. In Massachusetts, once the issue of criminal responsibility is properly raised by the evidence, the burden falls on the Commonwealth to prove beyond a reasonable doubt that the defendant was criminally responsible.
The rule is old, and the SJC has repeatedly declined invitations to abandon it. In Commonwealth v. Kostka, 370 Mass. 516 (1976), the court reaffirmed that the Commonwealth carries the burden of proving sanity beyond a reasonable doubt, while also holding that the jury may weigh the so called presumption of sanity, the common knowledge that most people are sane, as part of that calculus. In Commonwealth v. Keita, 429 Mass. 843 (1999), the court took a case for the stated purpose of considering whether to replace the common law rule with one requiring the defendant to prove lack of criminal responsibility by a preponderance of the evidence. It kept the rule. Chief Justice Wilkins’s opinion restated it plainly: “The Commonwealth had the burden of proving beyond a reasonable doubt that the defendant was criminally responsible at the time of the crime.” Keita also confirmed the countervailing points that give the prosecution a fighting chance under this framework. The Commonwealth may prove sanity without calling any expert at all. The jury may reject unanimous defense expert testimony. And the jury may infer sanity from the defendant’s conduct and the circumstances of the offense, along with the presumption of sanity, which the court candidly acknowledged sits in tension with placing the burden on the government.
How unusual is this nationally? After John Hinckley’s 1982 acquittal in the shooting of President Reagan, Congress and most state legislatures moved sharply the other way. The federal Insanity Defense Reform Act of 1984 requires a federal defendant to prove insanity by clear and convincing evidence, and it eliminated the volitional prong entirely. The large majority of states now place the burden on the defense by a preponderance or more. Massachusetts, along with a shrinking handful of states, still makes the government disprove insanity beyond a reasonable doubt and still retains both McHoul prongs. For a defense built on a documented psychiatric history, there is no better forum in the country on the law alone.
The practical consequence for this trial: if even one juror harbors a reasonable doubt about whether Clancy had substantial capacity to appreciate the wrongfulness of her conduct or to conform her conduct to law, that juror cannot vote to convict. The defense does not have to prove postpartum psychosis. It has to raise the issue, which the anticipated psychiatric evidence will plainly do, and then the Commonwealth must prove responsibility to the same standard it must prove every element of murder.
The Commonwealth’s theories of first degree murder
Before the jury ever reaches criminal responsibility, the Commonwealth must prove murder in the first degree. Prosecutors have signaled two theories.
Deliberate premeditation requires proof that the defendant decided to kill after a period of reflection. Massachusetts law does not require lengthy planning; the reflection can be brief. Expect the Commonwealth’s case to lean on timing and preparation evidence, including the sequence of events while Patrick Clancy was out of the house running errands, and any digital evidence such as searches that prosecutors contend shows planning. The defense will answer that apparent planning is not inconsistent with psychosis, and that a person acting on command hallucinations can act in an organized way. That collision, organization versus disorganization of mind, is where much of the expert testimony will land.
Extreme atrocity or cruelty is the second theory. Under Commonwealth v. Cunneen, 389 Mass. 216 (1983), jurors weigh a set of factors that includes indifference to or taking pleasure in the victim’s suffering, the consciousness and degree of suffering of the victim, the extent of physical injuries, the number of blows, the manner and force with which they were delivered, the instrument employed, and the disproportion between the means needed to cause death and those used. The alleged manner of death here, strangulation of three young children, is the kind of evidence prosecutors typically offer under this theory. Mental impairment evidence is relevant here too: even short of full lack of responsibility, the jury may consider a defendant’s mental condition in deciding whether the killing was committed with extreme atrocity or cruelty and whether premeditation existed.
What the jurors will actually weigh
Four categories of evidence will dominate.
- Expert psychiatric testimony. Both sides will call forensic experts on Clancy’s diagnosis and her mental state on January 24, 2023. Postpartum psychosis is a rare and severe condition, recognized as a psychiatric emergency, and the experts will dispute whether Clancy had it, whether she instead had depression or anxiety without psychotic features, and what either diagnosis meant for her capacity under McHoul.
- The medication history. Clancy’s treatment in the months before the killings, including the psychiatric medications she was prescribed and how they were adjusted, will be examined in detail. The defense views that history as documentation of a deteriorating patient; the Commonwealth views it as evidence of a person engaged with treatment who knew what she was doing.
- Lay observation testimony. Family members, friends, coworkers, and clinicians who saw Clancy in the days and hours around the killings will describe her demeanor. Under Keita, jurors may credit these observations over expert opinion in either direction.
- The premeditation evidence. The timing of the killings, the circumstances that placed her husband out of the home, and any electronic evidence will be offered both on premeditation and as circumstantial proof that Clancy appreciated the wrongfulness of her conduct.
The verdict slip
For each count, the jury’s realistic options are murder in the first degree, murder in the second degree, and not guilty by reason of lack of criminal responsibility. First degree murder carries a mandatory sentence of life without parole, followed by automatic review in the Supreme Judicial Court. Second degree murder carries life with parole eligibility. A finding of not criminally responsible is not release. It leads to commitment proceedings under G.L. c. 123, with hospitalization at a secure facility and periodic judicial review; a person found not criminally responsible for killings of this nature can expect confinement measured in years and revisited only through court supervised findings about mental illness and dangerousness. Clancy, who is paralyzed from a suicide attempt on the day of the killings, has been held at Tewksbury State Hospital throughout the case.
Honest expectations
Insanity defenses rarely succeed with juries. They are raised in a small fraction of felony cases and rejected in most of the cases where they are tried, and Massachusetts juries have returned first degree murder convictions in a series of high profile cases where the defense evidence of mental illness was substantial. Jurors are permitted to rely on the presumption of sanity, they may discount expert opinion, and the facts in filicide cases exert enormous emotional force in the Commonwealth’s favor.
That said, this case is a genuine contest, for two reasons grounded in law rather than sympathy. The burden rule means the defense wins the responsibility question on a reasonable doubt, not on affirmative proof. And the psychiatric history here is documented in treatment records created before January 24, 2023, not reconstructed afterward, which blunts the standard prosecution argument that the illness is a post hoc invention. Whether that is enough is exactly what twelve jurors, once selected, will be asked to decide. No one should pretend to know the answer today.
Three children died in Duxbury. Nothing in the legal analysis diminishes that, and the trial ahead will honor it only if the verdict rests on the evidence and the law rather than on the noise surrounding the courtroom. Opening statements are expected once a jury is seated. We will follow the trial as it unfolds.