The Lindsay Clancy Mistrial: How the Same Case Would Be Tried in New York

On September 4, 2026, Judge William Sullivan declared a mistrial in Commonwealth v. Lindsay Clancy after a Plymouth County jury deliberated for seven days and reported that it was hopelessly deadlocked. The split was reportedly 11–1, with the majority favoring a verdict of not guilty by reason of lack of criminal responsibility. Clancy, a labor and delivery nurse, never disputed that she killed her three children in their Duxbury home in January 2023. The only real question at trial was whether postpartum psychosis stripped her of criminal responsibility for it.

The case has been covered as a story about maternal mental health, and it is. But for anyone practicing criminal defense in New York, it is also a useful piece of comparative law. Massachusetts and New York ask juries very different questions in a case like this — and the differences are not academic. They change who has to prove what, what the jury is allowed to hear, what verdicts are even on the table, and what happens to the defendant afterward.

The Massachusetts Question — and Who Had to Answer It

Massachusetts applies the McHoul standard: a defendant is not criminally responsible if, because of mental disease or defect, she lacked substantial capacity either to appreciate the wrongfulness of her conduct or to conform her conduct to the requirements of law.

The critical feature is the burden. In Massachusetts, once the defense puts criminal responsibility genuinely in issue, the Commonwealth must prove beyond a reasonable doubt that the defendant was criminally responsible. The prosecutor in Duxbury had to convince twelve people, to a moral certainty, that a woman with a documented psychiatric collapse understood what she was doing. Eleven jurors were not convinced. One was, and that was enough to hang the case.

New York Flips the Burden — and That Is the Whole Ballgame

New York asks a similar substantive question but assigns the burden in the opposite direction.

Under Penal Law § 40.15, it is an affirmative defense that the defendant lacked criminal responsibility by reason of mental disease or defect — meaning she lacked substantial capacity to know or appreciate either (1) the nature and consequences of her conduct, or (2) that the conduct was wrong. Because § 40.15 is styled an affirmative defense, Penal Law § 25.00(2) puts the burden on the defendant to establish it by a preponderance of the evidence.

Read those two rules next to each other and the practical consequence is stark. In Massachusetts, a juror who is genuinely uncertain about a defendant’s sanity is instructed to acquit. In New York, that same uncertain juror is instructed to convict. Clancy’s defense won eleven jurors in a jurisdiction where doubt cut her way. In New York, the identical evidentiary record would have had to persuade jurors affirmatively — more likely than not — that she could not appreciate the wrongfulness of what she did.

There is a second structural difference that narrows the New York standard further. New York’s test asks whether the defendant could “know or appreciate” the nature of her conduct or its wrongfulness. It does not contain the second McHoul prong at all — the inability to conform one’s conduct to the law, often called the volitional prong. A New York defendant who understood that killing was wrong but could not stop herself has, on the face of the statute, no insanity defense. New York’s is a cognitive test only.

What New York Would Have Charged

Massachusetts charged first-degree murder, which carries a mandatory life sentence and left the jury with a stark all-or-nothing choice.

New York’s murder statutes do not map neatly onto that. Murder in the first degree (Penal Law § 125.27) requires a specific aggravating circumstance; the one that might arguably fit multiple deaths in a single episode is § 125.27(1)(a)(viii), and it is charged sparingly. Aggravated murder (§ 125.26) includes a provision for an intended victim under fourteen, but only where the defendant acted “in an especially cruel and wanton manner pursuant to a course of conduct intended to inflict and inflicting torture” — a demanding element that would not obviously be met here.

Realistically, a Nassau or Suffolk County indictment would charge three counts of murder in the second degree under § 125.25(1) — intentional murder, a class A-I felony carrying 15-to-25 years to life on each count.

The Middle Ground New York Has and Massachusetts Does Not

This is the difference that might have prevented a hung jury altogether.

New York recognizes extreme emotional disturbance as an affirmative defense to intentional murder. Under Penal Law § 125.25(1)(a)(i), a defendant who proves by a preponderance that she acted under the influence of an extreme emotional disturbance “for which there was a reasonable explanation or excuse” is not acquitted — she is convicted of manslaughter in the first degree under § 125.20(2), a class B violent felony carrying a determinate term of 5 to 25 years.

New York’s version is unusually defense-friendly. Since People v. Casassa, 49 N.Y.2d 668 (1980), the reasonableness of the explanation is judged subjectively — from the viewpoint of a person in the defendant’s situation, under the circumstances as the defendant believed them to be. No provocation by the victim is required.

The Clancy jury had two boxes to check: guilty of first-degree murder, or not criminally responsible. A New York jury would have had three. A juror unwilling to say “she is not responsible” but equally unwilling to brand her a murderer would have somewhere to land. That is often exactly the juror who hangs a case.

New York offers one more off-ramp Massachusetts does not: CPL § 220.15 permits a plea of not responsible by reason of mental disease or defect, with the district attorney’s consent and the court’s approval. A comparable New York case could be resolved without ever seating a jury.

Getting the Psychiatric Evidence In

Two New York rules deserve attention.

First, CPL § 250.10 conditions the admissibility of any psychiatric evidence on written notice served on the People and filed with the court, generally within thirty days of the not-guilty plea. Late notice is curable only “in the interest of justice and for good cause shown.” This is a genuine trap; a mental-health defense can be lost before the file is even fully reviewed.

Second, New York remains a Frye jurisdiction for novel scientific evidence, and its courts have been notably skeptical of syndrome testimony in exactly this setting. In People v. Wernick, 89 N.Y.2d 111 (1996), the Court of Appeals upheld the exclusion of defense expert testimony describing a psychological profile of women who kill their newborns, calling it “at best, a novel hypothesis” lacking general acceptance. The lesson for a New York defense is to diagnose the individual defendant — a brief psychotic disorder or bipolar disorder with peripartum onset, documented in her own medical records — rather than to prove the existence of a syndrome. Postpartum psychosis is not itself a standalone DSM-5 diagnosis, which was a live issue in Duxbury and would be a sharper one here.

“Not Responsible” Is Not a Walk — and the Jury Gets Told So

A frequent public misconception is that an insanity verdict means release. CPL § 330.20 says otherwise: the court immediately orders a psychiatric examination, holds a hearing, and places the defendant on one of three tracks. A defendant found to have a dangerous mental disorder is committed to a secure facility for six months, subject to a first retention order of up to one year and subsequent retention orders of up to two years each, with no ceiling. Orders of conditions run five years and are renewable.

New York does something most states do not: CPL § 300.10(3) requires the trial judge to explain those consequences to the jury. Jurors do not have to guess whether an acquittal means an open door. For the defense, that instruction is worth a great deal.

What Happens After a Hung Jury

A deadlocked jury is not an acquittal, and double jeopardy does not bar a second trial. New York follows the same rule: CPL § 310.60(1)(a) permits discharge of a deadlocked jury, and CPL § 280.10(3) treats the resulting mistrial as one of legal necessity, leaving the People free to retry. Plymouth County District Attorney Timothy Cruz has said no decision has been made; the parties return to court on September 28 on a defense motion to dismiss.

The Takeaway

Neither New York nor Massachusetts has an infanticide statute of the kind most of the developed world adopted decades ago, and New York — unlike Illinois — has no statute making postpartum mental illness a formal mitigating factor at sentencing. That leaves these cases to be litigated with general-purpose tools: a cognitive-only insanity test the defendant must prove, an extreme emotional disturbance defense that can convert murder into manslaughter, a strict notice statute, and a Frye standard that rewards individualized diagnosis over syndrome evidence.

Whether a mental-health defense is available in a particular case turns on facts, records, and timing — and the timing rules are unforgiving. If you or a family member is facing a serious charge in Nassau County, Suffolk County, or anywhere in the New York City area where psychiatric history may be relevant, the time to raise it is at the beginning of the case, not the end.

Hochhauser Criminal & DWI Defense
Richard Hochhauser
164 Jackson Street
Hempstead, NY 11550
516-939-1529
RH@Hochhauserlaw.com

This post discusses general principles of New York law and reporting on an out-of-state case. It is not legal advice and does not create an attorney-client relationship.