¶ 58. dissenting. The majority hold that forty years of Vermont law entrusting juries with the discretion to reduce murder to manslaughter based on evidence of a defendant’s diminished capacity rests on a meaningless semantic distinction — an analytic flaw — which once revealed compels its complete abandonment. As Holmes famously observed, however, the law is not built on ordered logic; it is built on human experience.6 At bottom, the law’s recognition that a defendant’s compromised mental condition may mitigate murder to manslaughter reflects a basic human instinct correlating punishment with fault. We innately perceive that, even if technically “sane,” a defendant so severely compromised by mental or emotional trauma that he or she lacks the normal capacity for self-control may be less culpable, and therefore deserving of the lesser — though not insubstantial — retribution reserved for manslaughter. The doctrine of diminished capacity simply recognizes that we are all human, and all deserving of the law’s mercy.
¶ 59. The majority maintain, nevertheless, that at least six decisions of this Court plus “a host of other prior cases” recognizing the defense of diminished capacity must be “overrule[d]” in order to avoid “a substantial departure from our *270longstanding [homicide] framework.” Ante, ¶¶ 34 n.4, 39. This is paradoxical, to say the least. If a decision to overrule four decades of settled law is not a “departure” from our established homicide framework, I cannot imagine what is.
¶ 60. Certainly our reasoning has been inconsistent, which may help to explain the majority’s uncertainty in deciding whether we are reaffirming prior law or overruling it. But I think that this tension reveals something else: a fundamental misunderstanding of the issue at the heart of this case. The essential question here is not, as the majority suggests, whether “malice” continues to imply something more than intent; it probably does not. Nor is the question whether some of our decisions were logically inconsistent in characterizing diminished capacity as intent-negating when voluntary manslaughter actually requires an intent to kill; they probably were.
¶ 61. What the majority overlook is that all of these decisions — however occasionally imperfect their logic — recognized a murder defendant’s basic right to persuade a jury to reduce the offense to manslaughter based on evidence of diminished capacity resulting from a mental disease or defect not amounting to insanity. The essential question here is why? Why has this Court consistently — until today — recognized this right? Understand this, and we may begin to understand how best to characterize such evidence, whether it be malice-negating, intent-negating, or something else entirely.
¶ 62. The answer begins with the common-law crime of manslaughter based on heat of passion, which this Court described more than 150 years ago in language that cannot be improved on today: an offense “committed with a real design and purpose to kill, but through the violence of sudden passion occasioned by some great provocation, which in tenderness for the frailty of human nature the law considers sufficient to palliate the [offense].” State v. McDonnell, 32 Vt. 491, 545 (1860) (quotation and emphasis omitted), overruled on other grounds by State v. Burpee, 65 Vt. 1, 8, 25 A. 964, 966 (1892). Over time, the notion that human “frailty” may “palliate” an offense from murder to manslaughter extended to other circumstances, including — most notably — diminished capacity, which we early defined as “legally applicable to [mental] disabilities not amounting to insanity ... to reduce the degree of the crime rather than to excuse its commission.” State v. Smith, 136 Vt. 520, 527, 396 A.2d 126, 130 (1978).
*271¶ 63. Despite the various unpersuasive efforts over time to correlate diminished capacity with one or another element of murder — ably dissected by the majority — the fact remains that, like heat of passion, it constitutes in essence an “extenuating circumstance” permitting a jury to “palliate” or “mitigate” the offense from murder to manslaughter. See State v. Johnson, 158 Vt. 508, 518-19 n.4, 615 A.2d 132, 138 n.4 (1992) (“In straightforward terminology, voluntary manslaughter is an intentional killing committed under extenuating circumstances that would mitigate, but not justify, the killing, such as provocation that would cause a reasonable person to lose self control”). Indeed, Justice Morse was absolutely correct, as well as remarkably prescient, in anticipating this issue twenty years ago in State v. Pelican, when he observed as follows:
Although we have spoken previously of diminished capacity as “negating” malice, the correct way of explaining its effect is as a defense mitigating the degree of homicide from murder to voluntary manslaughter. Like second degree murder, voluntary manslaughter is an intentional killing, but, unlike second degree murder, it is committed under extenuating circumstances that would mitigate, but not justify, the killing.
160 Vt. 536, 543, 632 A.2d 24, 29 (1993) (Morse, J., concurring) (quotation omitted); see also State v. Blish, 172 Vt. 265, 272, 776 A.2d 380, 386 (2001) (noting that the “critical factor” distinguishing murder from manslaughter is “the existence of mitigating circumstances”).
¶ 64. Diminished capacity thus operates precisely like heat-of-passion; it is not tied to a particular state-of-mind element but rather allows the jury to reduce the crime from second-degree murder to voluntary manslaughter if it concludes that the offense was committed under the influence of a mental disease or defect not resulting in insanity. This understanding not only reinforces Justice Morse’s clarifying insight in Pelican, and our observation in cases like Blish, concerning the critical distinction between murder and manslaughter. It also closely complements the definition of manslaughter endorsed by the distinguished authors of the Model Penal Code — and enacted in several states — as “a homicide which would otherwise be murder . . . committed under the influence of extreme mental or emotional disturbance for *272which there is reasonable explanation or excuse . . . determined from the viewpoint of a person in the actor’s situation under the circumstances as [the actor] believes them to be.” Model Penal Code §210.3 (1980).
¶ 65. As succinctly summarized by New York’s high court, “[t]he purpose of the extreme emotional disturbance defense is to permit the defendant to show that his actions were caused by a mental infirmity not arising to the level of insanity, and that he is less culpable for having committed them.” People v. Patterson, 347 N.E.2d 898, 907 (N.Y. 1976); see also State v. Dumlao, 715 P.2d 822, 829 (Haw. Ct. App. 1986) (noting that Hawaii’s manslaughter definition based on the Model Penal Code essentially “merge[d] the two concepts of heat of passion and diminished capacity”); McClellan v. Commonwealth, 715 S.W.2d 464, 468 (Ky. 1986) (explaining that “[e]xtreme emotional disturbance for which there is a reasonable explanation . . . reduces the degree of a homicide from murder to manslaughter [and] [i]n that respect . . . serves the same function as ‘acting in sudden heat of passion’ ”). Even in England, the source of so much of our common law, murder must be reduced to manslaughter if the jury finds that the defendant “was suffering from such abnormality of mind ... as substantially impaired [his or her] mental responsibility for [the] acts and omissions in doing . . . the killing.” Homicide Act, 1957, 6 & 7 Eliz. 2, c. 11, pt. I, § 2(1). As one scholar has explained, the English Homicide Act — like the Model Penal Code — “broadly sets out a policy for judges and juries to apply in assessing culpability, but does not use legally defined mental states as intermediaries.” P. Dahl, Legal and Psychiatric Concepts and the Use of Psychiatric Evidence in Criminal Trials, 73 Calif. L. Rev. 411, 440 (1985).
¶ 66. What prevents the majority from embracing this clear and straightforward approach and reaffirming a defense that has been available to Vermont defendants for nearly forty years? The majority assert that it would mark a “substantial departure” from Vermont law, yet recognize at the same time that we have continually — if not always consistently — characterized diminished capacity as fundamentally a defense in mitigation. The authority for this approach is plain. No dramatic “departure” is required to recognize it.
¶ 67. Perhaps a different concern animates the majority, however — the concern implicit in their suggestion that this under*273standing of diminished capacity lacks sufficient “standards” and thus leaves too much discretion to the jury. Ante, ¶ 38. But if so the premise is flawed. This Court’s shifting explanations for the doctrine notwithstanding, Vermont juries have applied the defense of diminished capacity for nearly forty years, and I am not aware of any suggestion, much less evidence, of jury nullification or confusion. There is simply no basis to believe that ordinary Vermonters are incapable of sensibly evaluating a plea in mitigation based upon evidence of significant mental trauma, to determine whether in the particular factual circumstances it warrants a reduction in the defendant’s culpability.
¶ 68. Moreover, taken to its logical conclusion, the majority’s belief that a defense divorced from the specific elements of murder lacks adequate “standards” would just as logically compel abrogation of heat-of-passion manslaughter, which we similarly define as a defense in mitigation — “an intentional killing committed under extenuating circumstances that would mitigate, but not justify, the killing, such as provocation that would cause a reasonable person to lose self control.” Johnson, 158 Vt. at 518-19 n.4, 615 A.2d at 138 n.4. All that distinguishes the two doctrines, in this sense, is the “reasonable person” test, an extraordinarily thin basis of distinction.
¶ 69. Indeed, the notion that heat-of-passion manslaughter might provide a more reliable or objective standard — predicated on whether a “reasonable” person would have been sufficiently provoked to kill — has been shown to be wholly illusory. The idea that, in assigning criminal culpability, a jury should largely ignore the mental state of the particular defendant and focus on whether a “reasonable” person would have committed the homicide has been aptly described as “absurd.” As one commentator has cogently observed:
“[I]t seems absurd to say that the reasonable man will commit a felony the possible punishment for which is imprisonment for life. To say that the “ordinary man” will commit this felony is hardly less absurd. . . .
Surely the true view of provocation is that it is a concession to the ‘frailty of human nature’ in those exceptional cases where the legal prohibition fails of effect. It is a compromise, neither conceding the propriety of the act nor exacting the full penalty for it.”
*274Dumlao, 715 P.2d at 827 (quoting G. Williams, Provocation and the Reasonable Man, 1954 Crim. L. Rev. 740, 742); see also State v. Ott, 686 P.2d 1001, 1005 (Or. 1984) (observing that the traditional heat-of-passion defense “placed the jury in the conceptually awkward (to put it kindly) position of having to determine when it is reasonable for a reasonable man to act unreasonably”); A. Donovan et al., Is the Reasonable Man Obsolete? A Critical Perspective on Self-Defense and Provocation, 14 Loy. L.A. L. Rev. 435, 451 (1981) (noting “paradox . . . inherent in the use of the reasonable standard to test criminal responsibility: the presence or absence of criminal intent is determined by a standard which ignores the mental state of the individual accused”).7
¶ 70. The notion that juries are reliably guided by identifiable public standards in deciding whether an “ordinary” or “reasonable” person would have intentionally killed under the circumstances is thus questionable, to say the least, and certainly provides no more objective guidance than expert evidence focused on the accused’s state of mind. Indeed, as one scholar has noted, focusing on the accused’s mental or emotional status actually “simplif[ies] the jury’s task because the inquiry into the accused’s own mental state is more concretely grounded in reality than are conjectures about a mythical reasonable man.” Donovan, supra, at 458.
¶ 71. Accordingly, I would hold that the trial court erred in refusing to instruct on diminished capacity where — as here — the record evidence amply supported such an instruction. Indeed, the facts here present a textbook case for the jury’s consideration of the diminished capacity defense. Based on numerous interviews with defendant and others, a clinical psychologist testified at length concerning defendant’s “enormously elevated” levels of psychological trauma resulting from a horrific history of domestic abuse. He concluded that defendant consequently suffered from “acute stress disorder,” entered a “dissociative state” when she became embroiled in a physical confrontation with the victim, and reacted “automatically and without conscious control” in attacking *275the victim with deadly force. The evidence was more than sufficient to warrant an instruction on diminished capacity, allowing the jury to determine whether defendant acted under the influence of a mental disease or defect not rising to the level of insanity.
¶ 72. In light of this evidence, furthermore, it is impossible to conclude that the error was harmless. Defendant’s claim of diminished capacity was a central theory of the defense. “A defendant is entitled to have the court present a defense based on the evidence to the jury squarely, that they might confront it, consider it, and resolve its truth or falsity by their verdict.” State v. Drown, 148 Vt. 311, 312, 532 A.2d 575, 576 (1987) (quotation omitted). The trial court’s instruction on manslaughter here entirely omitted from the jury’s consideration defendant’s core defense. Under any standard of fundamental fairness, this cannot be found to be harmless beyond a reasonable doubt, and compels reversal of the judgment. See State v. Duff, 150 Vt. 329, 333, 554 A.2d 214, 216 (1988) (reversing second-degree murder conviction based in part on court’s incomplete charge on diminished capacity, which referenced only heat of passion).
¶ 73. Today’s decision to abandon the settled defense of diminished capacity defies common sense, reason, and authority. Although our descriptions of the doctrine have not always been consistent, our commitment to its intrinsic justice has never wavered. This is because, like all good common-law principles, its source does not lie in case books — but in the human heart. The law is diminished if we forget this.
On Motion for Reargument
¶ 74. Appellant moves for reargument of this Court’s December 5, 2014 decision, in which we concluded “that the trial court correctly declined to instruct the jury that it could consider the evidence of defendant’s psychological condition as a basis for convicting her of voluntary manslaughter.” State v. Congress, 2014 VT 129, ¶ 1, 198 Vt. 241, 114 A.3d 1128. In seeking reargument, appellant argues for the first time that applying this holding retroactively to her, rather than prospectively only, violates the Due Process Clause of the Fourteenth Amendment to the United States Constitution. In so arguing, appellant relies upon Rogers v. Tennessee, in which the United States Supreme Court held that due process concerns prohibit retroactive application of “a judicial *276alteration of a common law doctrine of criminal law . . . only where [the alteration] is ‘unexpected and indefensible by reference to the law which has been expressed prior to the conduct in issue.’ ” 532 U.S. 451, 462 (2001) (quoting Bouie v. City of Columbia, 378 U.S. 347, 354 (1964)). In Rogers, the Court determined in relevant part that the Due Process Clause did not prohibit retroactive application of a state court decision abolishing a common law doctrine that precluded a defendant from being convicted of murder unless the victim died within a year and a day of the defendant’s act. 532 U.S. at 466-67. The Court reasoned that the state court decision was not “a marked and unpredictable departure from prior precedent,” but rather “a routine exercise of common law decisionmaking in which the court brought the law into conformity with reason and common sense.” Id.
¶ 75. The situation is similar here. As we explained in our opinion, many of our prior decisions suggesting that evidence of a defendant’s diminished mental capacity can “mitigate” criminal liability from murder to voluntary manslaughter defined the necessary diminution in mental capacity with reference to its effect on a defendant’s ability to form the necessary intent. State v. Congress, 2014 VT 129, ¶ 33. This Court has never clearly applied a framework under which diminished capacity could “mitigate” criminal liability from murder to manslaughter without negating the required intent element. Id. ¶ 37. Thus, our decision not to allow an instruction that would have permitted the jury in this case to convict defendant of voluntary manslaughter even if it concluded that she had the necessary intent was neither unexpected nor indefensible by reference to our law as expressed before the act in question. In short, applying our decision to the instant case cannot be construed as “the sort of unfair and arbitrary judicial action against which the Due Process Clause aims to protect.” Rogers, 532 U.S. at 467. Accordingly, defendant’s motion for reargument is denied.
“The life of the law has not been logic; it has been experience.” O.W. Holmes, Jr., The Common Law 1 (1881).
Tellingly, the defense of heat-of-passion or provocation originally “turned on the individual accused’s state of mind as revealed by all relevant facts and circumstances of the individual’s case” and was only modified to the so-called “reasonable” person standard when judges gave the decision to juries as “a device which promoted the myth of the objective, value-free nature of the criminal law.” Donovan, supra, at 447-48.