# Commonwealth v. Mattis > Massachusetts Supreme Judicial Court · January 11, 2024 URL: https://www.frixlaw.com/law-library/cases/9917022 ## Case - **Court:** Massachusetts Supreme Judicial Court - **Decided:** January 11, 2024 - **Precedential status:** Published - **Opinion:** Opinion - **Cited by:** 0 later opinions in the Frix Law Library ## Citator (automated) - No negative treatment found by the automated citator. That is not the same as a confirmation that the case is good law; read the citing cases. - Full citator and citing cases: https://www.frixlaw.com/law-library/cases/9917022 ## How later opinions describe it (automated extraction) - discussing applicability of Diatchenko I's reasoning to first prong of tripartite framework ## Opinion text NOTICE: All slip opinions and orders are subject to formal revision and are superseded by the advance sheets and bound volumes of the Official Reports. If you find a typographical error or other formal error, please notify the Reporter of Decisions, Supreme Judicial Court, John Adams Courthouse, 1 Pemberton Square, Suite 2500, Boston, MA, 02108-1750; (617) 557- 1030; SJCReporter@sjc.state.ma.us SJC-11693 COMMONWEALTH vs. SHELDON MATTIS. Suffolk. February 6, 2023. - January 11, 2024. Present: Budd, C.J., Gaziano, Lowy, Cypher, Kafker, Wendlandt, & Georges, JJ. Homicide. Constitutional Law, Sentence, Cruel and unusual punishment, Parole. Parole. Practice, Criminal, Sentence, Parole. Indictments found and returned in the Superior Court Department on December 21, 2011. Following review by this court, 484 Mass. 742 (2020), findings of fact and a ruling of law were issued by Robert L. Ullmann, J. Ryan M. Schiff (Paul R. Rudof & Ruth Greenberg also present) for the defendant. Cailin M. Campbell, Special Assistant District Attorney (John C. Verner, Assistant District Attorney, also present) for the Commonwealth. The following submitted briefs for amici curiae: Darina Shtrakhman, of California, Matt K. Nguyen, of the District of Columbia, & Adam Gershenson for Jeffrey Aaron & others. Andrea Lewis Hartung, of Illinois, & Marsha L. Levick, of Pennsylvania, & Oren Nimni for the Sentencing Project & others. 2 Jonathan W. Blodgett, District Attorney for the Eastern District, & David F. O'Sullivan, Assistant District Attorney, for District Attorney for the Eastern District & another. Jasmine Gonzales Rose, of Oregon, Duke K. McCall, III, & Douglas A. Hastings, of the District of Columbia, Robert S. Chang, of Washington, Caitlin Glass, Neda Khoshkhoo, & Katharine Naples-Mitchell for Boston University Center for Antiracist Research & others. Kenneth J. Parsigian, Avery E. Borreliz, Erin M. Haley, & Martin W. Healy for Carol S. Ball & others. Benjamin H. Keehn, Committee for Public Counsel Services, & John J. Barter for Committee for Public Counsel Services. BUDD, C.J. When it comes to determining whether a punishment is constitutional under either the Eighth Amendment to the United States Constitution or art. 26 of the Massachusetts Declaration of Rights, youth matters. See, e.g., Miller v. Alabama, 567 U.S. 460 (2012); Graham v. Florida, 560 U.S. 48 (2010); Roper v. Simmons, 543 U.S. 551 (2005); Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 655 (2013) (Diatchenko I), S.C., 471 Mass. 12 (2015). In Miller, supra at 465, 476, the United States Supreme Court struck down mandatory life imprisonment without the possibility of parole for juveniles based in part on the "mitigating qualities of youth." Approximately one and one-half years later, this court went further than Miller and concluded that sentencing a juvenile to life without parole in any circumstance would violate art. 26. See Diatchenko I, supra at 669-670. The defendant, Sheldon Mattis, was convicted of murder in the first degree, among other charges, and was sentenced to a 3 mandatory term of life in prison without the possibility of parole, see G. L. c. 265, § 2 (a). Commonwealth v. Watt, 484 Mass. 742, 754-756 (2020). On appeal, he challenged the constitutionality of his sentence as applied to him. He argued that because he was eighteen years old at the time of the murder, he is entitled to the same protection as juvenile offenders (i.e., those from fourteen to seventeen years of age) convicted of murder in the first degree, who receive a term of life with the possibility of parole. See G. L. c. 265, § 2 (b). Here, we consider whether our holding in Diatchenko I should be extended to apply to emerging adults, that is, those who were eighteen, nineteen, and twenty years of age when they committed the crime.1 Based on precedent and contemporary standards of decency2 in the Commonwealth and elsewhere, we conclude that the answer is yes.3 1 For the purposes of this opinion, "emerging adult" is defined as someone who is eighteen, nineteen, or twenty years of age. Although the record contains some references to individuals who are as old as twenty-four years of age as "emerging adults," the focus of the record and the Superior Court judge's factual findings, which guide our analysis today, are limited to offenders who are aged eighteen, nineteen, or twenty at the time of the crime. 2 As discussed infra, our understanding of contemporary standards of decency is informed by the updated scientific record. 3 We acknowledge the amicus briefs submitted by (1) twenty- three retired Massachusetts judges, Boston Bar Association, and Massachusetts Bar Association; (2) seventeen neuroscientists, 4 Background. 1. The homicide. The evidence presented in the defendant's trial is summarized in Watt, 484 Mass. at 744- 745.4 We provide a condensed version of events as the jury could have found them. On September 25, 2011, the defendant; his codefendant, Nyasani Watt; and another friend observed Kimoni Elliott standing outside a nearby convenience store. Id. at 744. The defendant approached Elliott on a bicycle and asked him where he was from. Elliott replied, "Everton." Id. The two then parted ways. Id. Elliott met Jaivon Blake in a nearby parking lot while the defendant returned to Watt and said, "[B]e easy, because that's them kids." Watt, 484 Mass. at 744-745. A few minutes later, when Elliott and Blake were in view, the defendant handed Watt a gun and told Watt "to go handle that." Id. at 745. Watt rode toward Elliott and Blake on a bicycle and shot them from behind. Id. Elliott survived gunshot wounds to his neck and right arm, psychologists, and criminal justice scholars; (3) Sentencing Project, Juvenile Law Center, and Roderick and Solange MacArthur Justice Center; (4) the Committee for Public Counsel Services; (5) Boston University Center for Antiracist Research, Fred T. Korematsu Center for Law and Equality, Center on Race, Inequality, and the Law, and Criminal Justice Institute at Harvard Law School; and (6) the district attorney for the Eastern district and the district attorney for the Plymouth district. The defendant and Watt were tried together, and their 4 appeals were consolidated. The decision was published under Watt's name. 5 but Blake died from a single gunshot wound to the torso. Id. at 744. 2. Procedural history and development of the record. In 2013, the defendant and Watt were tried jointly and convicted of murder in the first degree on the theories of deliberate premeditation and extreme atrocity or cruelty, among other charges. Watt, who was seventeen at the time of the shooting, received a life sentence with the possibility of parole after fifteen years.5 Watt, 484 Mass. at 745. See G. L. c. 265, § 2 (b). See also G. L. c. 127, § 133A; G. L. c. 279, § 24. The defendant, who had turned eighteen approximately eight months prior to the crime, received a life sentence without the possibility of parole. Watt, supra. See G. L. c. 265, § 2 (a). See also G. L. c. 127, § 133A. Each defendant filed a motion for a new trial. Among other things, the defendant argued that his mandatory sentence of life without parole violated art. 26's prohibition of cruel or unusual punishment because he was under twenty-two years of age when he committed the murder. A Sentencing in this case occurred after the United States 5 Supreme Court's decision in Miller, but mere days before we issued our decision in Diatchenko I. Despite not yet having our guidance on how to sentence such juveniles in the absence of new legislation on the matter, the judge correctly sentenced Watt to the equivalent penalty for murder in the second degree -- the "next-most severe sentence under the sentencing statute" available at the time for a juvenile convicted of murder in the first degree. See Watt, 484 Mass. at 753. 6 Superior Court judge denied both motions, and the appeals from these denials were consolidated with the defendants' direct appeals. Watt, supra at 743-744. We unanimously upheld the denial of both defendants' postconviction motions and affirmed all convictions. Watt, 484 Mass. at 765. However, we remanded the defendant's case6 to the Superior Court for "development of the record with regard to research on brain development after the age of seventeen[, which] will allow us to come to an informed decision as to the constitutionality of sentencing young adults to life without the possibility of parole." Id. at 756. A Superior Court judge, who had also been the trial judge, conducted three days of evidentiary hearings during which three expert witnesses -- neuroscientist Dr. Adriana Galván, forensic psychologist7 Dr. Robert Kinscherff, and forensic psychologist Dr. Stephen Morse -- testified on the topic of adolescent neurological and psychological development after the age of seventeen.8 The defendant also entered in the record the 6 Because the art. 26 question did not apply to Watt, we remanded only the defendant's case to the Superior Court. Watt, 484 Mass. at 765. 7 "[F]orensic psychology [i]s the use of psychological theories and methods and data to help the legal system resolve legal questions." 8 The parties agree that all of the experts who submitted evidence in the record are duly qualified in the relevant fields 7 transcript of the testimony of a fourth expert witness, developmental psychologist Dr. Laurence Steinberg.9 The of neuroscience and forensic psychology, among other specialties, and are recognized as leaders in their respective professional fields. Galván holds a Ph.D. in neuroscience and is a tenured professor of psychology at the University of California, Los Angeles (UCLA), as well as the director of UCLA's Developmental Neuroscience Lab. She has coauthored over one hundred book chapters and peer-reviewed studies, many of which have been published in leading journals in her field. She has received numerous honors and awards, including the Presidential Early Career Award for Scientists and Engineers as well as the Troland Award from the National Academy of Sciences. Kinscherff holds both a juris doctor and a Ph.D. in clinical psychology. He is a professor in the doctoral psychology program at William James College. He has been qualified as an expert in forensic psychology numerous times and was formerly the Assistant Commissioner for Forensic Mental Health at the Department of Mental Health. Morse holds both a juris doctor and a Ph.D. in psychology and social relations. He is a tenured professor of law and professor of psychology and law at the University of Pennsylvania. He has written numerous articles on neuroscience and the law, many of which have been published in leading journals on law and neuroscience. He has been qualified as an expert in at least twenty cases and was previously the Legal Director at the MacArthur Foundation's Law and Neuroscience Project. Galván and Kinscherff testified on behalf of the defendant. Morse testified on behalf of the Commonwealth. 9 Steinberg holds a Ph.D. in human development and family studies. He is a tenured professor at Temple University. Over the course of forty years, he has authored scores of studies that have been published in peer-reviewed journals, including top journals in his field. He has been qualified as an expert in developmental psychology approximately thirty times. His research was cited in two of the leading Supreme Court cases on the Eighth Amendment's ban on cruel and unusual punishment as 8 Commonwealth and the defendant also submitted voluminous exhibits, including numerous scientific studies on adolescence and neurobiological maturity. The record was transmitted to us in May 2021 but did not include factual findings. In December 2021, we again remanded this case, along with the case underlying our decision in Commonwealth v. Robinson, 493 Mass. (2023), to the Superior Court for the development of factual findings based on the previously transmitted record.10 Specifically, we requested findings regarding "whether the imposition of a mandatory sentence of life without the possibility of parole for . . . those convicted of murder in the first degree who were eighteen to twenty-one at the time of the crime, violates [art.] 26." A different Superior Court judge issued factual findings in July 2022, concluding that the mandatory imposition of a sentence of life without parole for offenders who were eighteen, applied to juveniles. See Miller, 567 U.S. at 471 (referencing Steinberg & Scott, Less Guilty by Reason of Adolescence: Developmental Immaturity, Diminished Responsibility, and the Juvenile Death Penalty, 58 Am. Psychologist 1009, 1014 [2003]); Roper, 543 U.S. at 569-573 (same). Steinberg testified on behalf of the defendant in the case underlying our decision in Commonwealth v. Robinson, 493 Mass. (2023), a case raising a nearly identical sentencing claim. See note 10, infra. 10This case was paired with the one underlying Robinson, 493 Mass. , because, similarly to Mattis, Robinson asked this court to consider whether a sentence of life without parole is constitutional when applied to those who committed their crime while under twenty-one years of age. 9 nineteen, or twenty years old at the time they committed the crime is a violation of art. 26. In particular, the judge found that emerging adults are "less able to control their impulses" and that "their reactions in [emotionally arousing] situations are more similar to those of [sixteen and seventeen year olds] than they are to those [twenty-one to twenty-two] and older." The case and its entire evidentiary record subsequently were transmitted back to this court, where the defendant argued that it is unconstitutional to sentence an emerging adult to life without the possibility of parole in any circumstance, and the Commonwealth argued that such a sentence is constitutional if imposed after an individualized hearing. Discussion. Adopted in 1780, art. 26 states: "No magistrate or court of law, shall . . . inflict cruel or unusual punishments." In evaluating the constitutionality of a sentence, this court is guided by "[t]he fundamental imperative of art. 26 that criminal punishment be proportionate to the offender and the offense." Diatchenko I, 466 Mass. at 671. A punishment is unconstitutional (i.e., cruel or unusual) if it is so disproportionate to the crime that it "shocks the conscience and offends fundamental notions of human dignity." Id. at 669, quoting Cepulonis v. Commonwealth, 384 Mass. 495, 497 (1981).11 11Similarly, the Eighth Amendment's prohibition on cruel and unusual punishment "flows from the basic 'precept of justice 10 1. Constitutional framework. To evaluate the proportionality of a mandatory life sentence imposed on a category of offenders (here, emerging adults), we look to precedent as well as what contemporary standards of decency, as defined by objective indicia, require. See Graham, 560 U.S. at 61, quoting Roper, 543 U.S. at 563-564 ("The Court first considers 'objective indicia of society's standards, as expressed in legislative enactments and state practice,' to determine whether there is a national consensus against the sentencing practice at issue. . . . [Then] guided by 'the standards elaborated by controlling precedents and by the Court's own understanding and interpretation of the Eighth Amendment's text, history, meaning, and purpose,' . . . the Court must determine . . . whether the punishment in question violates the Constitution"); Roper, supra at 560-561.12 As for that punishment for crime should be graduated and proportioned' to both the offender and the offense." Miller, 567 U.S. at 469, quoting Roper, 543 U.S. at 560. 12The dissent asserts that the "tripartite" test is the proper tool to analyze the constitutionality of the sentence here. Post at . See Commonwealth v. Jackson, 369 Mass. 904, 910-916 (1976). That test considers (1) the nature of the offense and the offender in light of the degree of harm to society, (2) the sentence imposed and penalties prescribed for more serious crimes in Massachusetts, and (3) a comparison between the sentence imposed with the penalties prescribed for the same offense in other jurisdictions. It traditionally has been used, both by this court and the Supreme Court, to assess whether a term-of-years sentence is grossly disproportionate to a given offense, considering all the circumstances of a 11 the latter, current scientific consensus regarding the characteristics of the class can help determine the contemporary standards of decency pertaining to that class. See Diatchenko I, 466 Mass. at 659-661, 669-671. See also Miller, 567 U.S. at 471-472 ("Our decisions rested not only on common sense . . . but on science and social science as well"); Graham, supra at 68; Roper, supra at 569-570; Commonwealth v. Okoro, 471 Mass. particular case. Id. See, e.g., Commonwealth v. Sharma, 488 Mass. 85, 89-90 (2021); Commonwealth v. LaPlante, 482 Mass. 399, 403 (2019); Commonwealth v. Perez, 477 Mass. 677, 685-686 (2017), S.C., 480 Mass. 562 (2018); Opinions of the Justices, 378 Mass. 822, 824-825 (1979). See also Ewing v. California, 538 U.S. 11 (2003); Harmelin v. Michigan, 501 U.S. 957 (1991); Solem v. Helm, 463 U.S. 277 (1983). Although the tripartite test incorporates elements of the approach we use today, it is of limited utility here. Its "threshold comparison between the severity of the penalty and the gravity of the crime does not advance the analysis" where neither the sentence's proportionality to the charged offense nor the existence of a more serious offense in the Commonwealth is being challenged. See Graham, 560 U.S. at 61. Rather, our cases show, and Supreme Court precedent affirms, that it is the "categorical" framework, which focuses on contemporary standards of decency, that applies here, where the task is to assess whether a sentence is disproportionate when applied to an entire category of offenders. See id. ("In cases turning on the characteristics of the offender, the Court has adopted categorical rules . . . [and] consider[ed] 'objective indicia of society's standards'"); Diatchenko I, 466 Mass. at 669 (contemporary standards of decency render imposition of life without parole sentence on particular category of offenders unconstitutionally disproportionate). See also, e.g., Roper, 543 U.S. at 560-563 (standards of decency dictate death penalty's unconstitutionality when imposed on those under eighteen); Atkins v. Virginia, 536 U.S. 304, 321 (2002) (standards of decency dictate death penalty's unconstitutionality when imposed on those with intellectual disabilities). 12 51, 60 (2015) ("the determination that youth are constitutionally distinct from adults for sentencing purposes has strong roots in recent developments in the fields of science and social science"). a. Precedent. In a series of cases responding to challenges to juvenile sentences, the Supreme Court has consistently opined that the "mitigating qualities of youth" must be taken into consideration when it comes to sentencing. Johnson v. Texas, 509 U.S. 350, 367 (1993). See, e.g., Jones v. Mississippi, 141 S. Ct. 1307, 1314 (2021), citing Miller, 567 U.S. at 476; Johnson, supra ("A sentencer in a capital case must be allowed to consider the mitigating qualities of youth in the course of its deliberations over the appropriate sentence"). For example, when striking down the death penalty for juveniles in Roper, the Court discussed the "relevance of youth as a mitigating factor" at length, concluding that "[o]nce the diminished culpability of juveniles is recognized, it is evident that the penological justifications for the death penalty apply to them with lesser force than to adults." Roper, 543 U.S. at 570-571. In Graham, 560 U.S. at 76, the Court noted that an "offender's age is relevant to the Eighth Amendment, and criminal procedure laws that fail to take defendants' youthfulness into account at all would be flawed." The Court 13 concluded that it was unconstitutional to sentence juveniles who did not commit homicide to life without parole because they lack the maturity to be classified among the worst offenders deserving of the harshest punishments. The Court further noted that although "[m]aturity can lead to that considered reflection which is the foundation for remorse, renewal, and rehabilitation . . . [a] young person who knows that he or she has no chance to leave prison before life's end has little incentive to become a responsible individual."13 Id. at 79. More recently in Miller, 567 U.S. at 476, in which the Court held that a judge must be able to consider "mitigating qualities of youth" in formulating a sentence, the Court reiterated that youth is not simply a "chronological fact" (citation omitted). Rather, "[i]t is a time of immaturity, irresponsibility, impetuousness[,] and recklessness. . . . It is a moment and condition of life when a person may be most susceptible to influence and to psychological damage. . . . And its signature qualities are all transient" (citations and quotations omitted). Id. As a result, the Court reasoned, the Eighth Amendment forbids a sentencing scheme that mandates life 13Although Graham's ban on life sentences without the possibility of parole for juveniles applied only to nonhomicide crimes, as the Miller Court pointed out, "none of what [Graham] said about children -- about their distinctive (and transitory) mental traits and environmental vulnerabilities -- is crime- specific." Miller, 567 U.S. at 473. 14 without parole for juvenile offenders because such a scheme precludes a consideration of youth and the circumstances and characteristics attendant to it. Id. at 479. Approximately one and one-half years after Miller was decided, we considered whether sentencing a juvenile offender to life without the possibility of parole comported with art. 26. See Diatchenko I, 466 Mass. at 661. Ultimately, this court went further than Miller and concluded that because it is not possible to demonstrate that a juvenile offender is "irretrievably depraved," under the Massachusetts Declaration of Rights, such a sentence is cruel or unusual as imposed on a juvenile in any circumstance. Id. at 670-671. Central to each of the foregoing cases is the "fundamental precept of justice that punishment for crime should be graduated and proportioned to both the offender and the offense" (citation and quotations omitted). Id. at 669. Until now, we have declined to consider extending Diatchenko I to offenders eighteen years of age and older. See Watt, 484 Mass. at 755- 756, and cases cited. However, we also recognized that "researchers continue to study the age range at which most individuals reach adult neurobiological maturity . . . and that such research may relate to the constitutionality of sentences of life without parole for individuals other than juveniles" (citation and quotation omitted). Id. The judge's findings in 15 this case, described more fully infra, confirm that the brains of emerging adults are similar to those of juveniles. b. Contemporary standards of decency. An assessment of a punishment's proportionality occurs "in light of contemporary standards of decency which mark the progress of society." Diatchenko I, 466 Mass. at 669, quoting Good v. Commissioner of Correction, 417 Mass. 329, 335 (1994). See Okoro, 471 Mass. at 61 (proportionality of punishment is determined based on "the evolving standards of decency that mark the progress of a maturing society" [citation omitted]). Here, we consider the updated research on the brains of emerging adults, as well as the way emerging adults are treated in the Commonwealth and elsewhere, to determine whether a sentence of life without the possibility of parole is proportionate and thus constitutional when imposed upon that class of offenders. i. Science and social science. As mentioned supra, where modern scientific consensus regarding a particular class exists, it can be useful in determining the contemporary standards of decency as they relate to that class. See Miller, 567 U.S. at 471-472; Okoro, 471 Mass. at 59-60. Advancements in scientific research have confirmed what many know well through experience: the brains of emerging adults are not fully mature. Specifically, the scientific record strongly supports the contention that emerging adults 16 have the same core neurological characteristics as juveniles have. As the Superior Court judge noted, "Today, neuroscientists and behavioral psychologists know significantly more about the structure and function of the brains of [eighteen] through [twenty year olds] than they did [twenty] years ago . . . ." This is the result of years of targeted research and greater access to relatively new and sophisticated brain imaging techniques, such as structural magnetic resonance imaging (sMRI) and functional magnetic resonance imaging (fMRI).14 From the detailed evidence produced in the record, the judge made four core findings of fact regarding the science of emerging adult brains: emerging adults (1) have a lack of impulse control similar to sixteen and seventeen year olds in emotionally arousing situations,15 (2) are more prone to risk taking in pursuit of rewards than those under eighteen years and those over twenty-one years, (3) are more susceptible to peer 14 sMRIs allow researchers to examine the brain's anatomical structures at particular moments in time; fMRIs allow researchers to examine the brain's activation and responses to stimuli and environmental context. As Galván testified, MRIs, particularly sMRIs, have allowed researchers "to see [a] fine grain view of the brain that other technologies would not allow." 15This also is referred to as being under "hot cognition." The experts testified that under "cold cognition," which is the absence of emotionally arousing circumstances, the emerging adult brain functions much more similarly to the older adult brain than to the adolescent brain. 17 influence than individuals over twenty-one years, and (4) have a greater capacity for change than older individuals due to the plasticity of their brains. The driving forces behind these behavioral differences are the anatomical and physiological differences between the brains of emerging and older adults. See Steinberg, A Social Neuroscience Perspective on Adolescent Risk-Taking, 28 Developmental Rev. 78, 82-84, 85-89 (2008). These structural and functional differences make emerging adults, like juveniles, "particularly vulnerable to risk-taking that can lead to poor outcomes." We discuss each of the judge's four core factual findings in turn. A. Impulse control. The judge found that in terms of impulse control, emerging adults are more similar to sixteen and seventeen year old juveniles than to older adults. That is, they are less able to control their impulses in emotionally arousing situations. This finding is well supported by the record. Emerging adults still are experiencing the effects of "the sharp increase during puberty of certain hormones," lack a fully developed prefrontal cortex, which is "the part of the brain that most clearly regulates impulses," and lack fully developed connections "between the prefrontal cortex and other parts of the brain . . . that most clearly respond[] to rewards and 18 reward-related decision making." All four experts agreed that compared to older adults, emerging adults are more impulsive, more concerned with their immediate circumstances, and less able to envision future consequences. Galván explained that at least part of this distinction between emerging and older adults can be traced to differences in brain structure between the groups. "[T]he prefrontal cortex is the home for these abilities that we might say are what makes us adults . . . the ability to reason, the ability to think about how your actions today will have implications for the future." As the brain matures, it "undergoes a process called pruning and [eliminates]" synapses and neurons that are not needed. Advancements in sMRI data have allowed researchers "to measure this cortical thickness and thinning and the process continues through [eighteen], [nineteen], [twenty] years old." All of the other experts, including the Commonwealth's expert, agreed that the prefrontal cortex, an area of the brain associated with controlling impulses, is among the last brain regions to develop, and continues developing until the early to mid-twenties. See Icenogle et al., Adolescents' Cognitive Capacity Reaches Adult Levels Prior to Their Psychosocial Maturity: Evidence for a "Maturity Gap" in a Multinational, Cross-Sectional Sample, 43 Law & Hum. Behav. 69, 70 (2019); Sowell & others, In Vivo Evidence for Post-Adolescent Brain 19 Maturation in Frontal and Striatal Regions, 2 Nature Neurosci. 859, 860-861 (1999); Steinberg et al., Around the World, Adolescence Is a Time of Heightened Sensation Seeking and Immature Self-Regulation, Developmental Sci., vol. 21, Mar. 2018, at 1-4, 15-17. B. Risk taking in pursuit of reward. The judge found that "[a]s a group, [individuals eighteen through twenty years of age] in the United States and other countries are more prone to 'sensation seeking,' which includes risk-taking in pursuit of rewards, than are individuals under age [eighteen] and over age [twenty-one]." This finding similarly is well supported by the record. All of the experts agreed that emerging adults are more likely than children or older adults to engage in risky behavior and that risky behaviors tend to peak in late adolescence to early adulthood and then decline, with some experts asserting that this behavior plateaus around twenty-two years of age. Galván explained that fMRI studies evaluating the brain have shown that in individuals at least seventeen years of age, and up to twenty-one years of age, there is greater activity in the nucleus accumbens, a part of the brain associated with sensation seeking, than in older adults. Additionally, fMRI studies have shown that the ventral striatum, a part of the brain that correlates with risk-taking behaviors, also is more active among 20 late adolescents and early adults than it is in older adults. This research tracks numerous real-world behaviors. Emerging adults are overrepresented in multiple types of risky behavior, such as risky sexual behavior and risky driving behavior, in addition to risky criminal behavior. See Roper, 543 U.S. at 569, quoting Arnett, Reckless Behavior in Adolescence: A Developmental Perspective, 12 Developmental Rev. 339 (1992) ("It has been noted that 'adolescents are overrepresented statistically in virtually every category of reckless behavior'"). Each expert discussed the so-called "age-crime curve," which is a widely recognized phenomenon illustrating that criminal behavior crests at some point from late adolescence to early adulthood before significantly declining. Put succinctly, as with those under eighteen years of age, "late adolescence[16] 16All the experts referred to individuals from eighteen to twenty years of age as "late adolescents." We refer to this age group as "emerging adults." We do not agree with the dissent that this appellation indicates that we improperly are veering into the Legislature's lane. As the Supreme Court noted when it declared the death penalty unconstitutional for juveniles, line drawing is a necessary task when considering categorical bans on unconstitutional sentences. Roper, 543 U.S. at 574 ("Drawing the line at [eighteen] years of age is subject, of course, to the objections always raised against categorical rules. The qualities that distinguish juveniles from adults do not disappear when an individual turns [eighteen]. By the same token, some under [eighteen] have already attained a level of maturity some adults will never reach. For the reasons we have discussed, however, a line must be drawn"). 21 is a period in human development of increased risk taking, greater reactivity to high stress or highly emotionally arousing events and certain kinds of cognitive biases that, for example, lead them [(i.e., juveniles and emerging adults)] to not appraise a risk and apply it to themselves in the same way that an adult would." See Galván et al., Earlier Development of the Accumbens Relative to Orbitalfrontal Cortex Might Underlie Risk- Taking Behaviors in Adolescents, 26 J. Neurosci. 6885, 6885-6892 (2006); Hawes et al., Modulation of Reward-Related Neural Activation on Sensation Seeking across Development, 283 NeuroImage 763, 763-771 (2017); Rudolph et al., At Risk of Being Risky: The Relationship Between "Brain Age" under Emotional States and Risk Preference, Developmental Cognitive Neurosci., vol. 24, 2017, at 93-106; Steinberg et al., Around the World, Adolescence Is a Time of Heightened Sensation Seeking and Immature Self-Regulation, supra at 1-4, 15-17. C. Peer influence. The judge also found that emerging adults "are more susceptible to peer influence" than older adults and that the presence of peers makes emerging adults "more likely to engage in risky behavior." All four experts agreed that current research supports this conclusion. Steinberg's research in particular focuses on the ways in which the presence of peers affects decision-making and risk taking among different age groups. In his work, he has found 22 that "even if the peers aren't explicitly encouraging anything, the mere presence of peers increases the likelihood that adolescents[17] will engage in [risky] behavior." Although the presence of peers may influence behavior at any age, "peer influence is a much more serein [sic] and powerful factor during adolescence[18] than it is during adulthood." See Breiner et al., Combined Effects of Peer Presence, Social Cues, and Rewards on Cognitive Control in Adolescents, 60 Developmental Psychobiology 292, 292-302 (2018); Galván, Adolescent Brain Development and Contextual Influences: A Decade in Review, 31 J. Res. on Adolescence 843, 852-853 (2021); Silva et al., Peers Increase Late Adolescents' Exploratory Behavior and Sensitivity to Positive and Negative Feedback, 26 J. Res. on Adolescence 696, 696-705 (2015). D. Capacity for change. Finally, the judge found that emerging adults "have greater capacity to change than older individuals because of the plasticity of the brain during these years." This finding is well supported by the record. "[P]lasticity refers to the ability [to] change in response to the environment."19 Although the brain has its greatest 17 See note 16, supra. 18 See note 16, supra. 19Galván explained that plasticity primarily occurs in the hippocampus, which is "a small brain region in the deep layers 23 plasticity in the early months of life, as Galván explained, "[t]he second wave [of plasticity] is during adolescence."20 In contrast, "adult capacity for change is diminished because" the fully mature brain is much less malleable. Although the brain continues to change throughout one's lifespan, Steinberg testified that brain maturation is largely complete by as early as twenty-two years of age, and possibly up to twenty-five years of age. The Commonwealth's expert agreed that "[m]ost adolescents[21] even those who commit serious crimes will age out of offending and will not become career criminals." See Roper, 543 U.S. at 570, quoting Johnson, 509 U.S. at 368, and citing Steinberg & Scott, Less Guilty by Reason of Adolescence: Developmental Immaturity, Diminished Responsibility, and the Juvenile Death Penalty, 58 Am. Psychologist 1009, 1014 (2003) ("the signature qualities of youth are transient; as individuals mature, the impetuousness and recklessness that may dominate in younger years can subside"). See also Cauffman et al., A Developmental Perspective on Adolescent Risk-Taking and Criminal Behavior, c. 6 in The Handbook of Criminological Theory (2015); of the brain that has mostly been studied in the context of learning because plasticity or any plasticity-based changes are because we've learned something new." 20 See note 16, supra. 21 See note 16, supra. 24 Galván, Insights about Adolescent Behavior, Plasticity, and Policy from Neuroscience Research, 83 Neuron 262, 264 (2014). The evidence outlined supra provides a scientifically informed view of emerging adults' culpability and factors into our analysis whether contemporary standards of decency permit sentencing that cohort to life without the possibility of parole. ii. Treatment of emerging adults in the Commonwealth and elsewhere. To determine our contemporary standards of decency, in addition to referring to our own State statutes, see Good, 417 Mass. at 335, we may look to other policies and programs in the Commonwealth, our precedent, other States' statutes, as well as other States' judicial rulings, and even international statutes and decisions, among other sources, see Okoro, 471 Mass. at 61 (we commonly look to "judicial opinions and legislative actions at the State, Federal, and international levels," which "help to inform our understanding of what art. 26 protects" [citation omitted]). See also Thompson v. Oklahoma, 487 U.S. 815, 821-831 (1988) (looking to State statutes and death penalty juries to divine contemporary standards of decency, and noting consistency with practices of other nations); Enmund v. Florida, 458 U.S. 782, 788 (1982) (looking to "historical development of the punishment at issue, legislative judgments, international opinion, and the sentencing 25 decisions juries have made"); Coker v. Georgia, 433 U.S. 584, 596 (1977) ("important to look to the sentencing decisions that juries have made in the course of assessing whether capital punishment is an appropriate penalty"). As discussed infra, a combination of statutes passed here and elsewhere, as well as recent decisions in Washington and Michigan, indicate that our contemporary standards of decency do not support imposing life without parole sentences on emerging adults. To begin, the Legislature has determined that emerging adults require different treatment from older adults, specifically in the penological context. For example, the Department of Youth Services (department) statutorily is authorized to maintain custody of young people adjudicated as youthful offenders up to twenty-one years of age. See Commonwealth v. Terrell, 486 Mass. 596, 599-600, 603 (2021); G. L. c. 119, § 58. This sentencing scheme also permits the imposition of "dual" sentences for youthful offenders, requiring them to remain in the department's custody until they are twenty-one years of age before beginning their "adult sentence" at a house of correction. G. L. c. 119, § 58 (b). Further, in 2018, as part of a set of sweeping reforms, the Legislature authorized the Department of Correction and county houses of correction to "establish young adult correctional units." These units provide "targeted interventions, age 26 appropriate programming and a greater degree of individual attention" for individuals in custody "ages [eighteen] to [twenty-four]." G. L. c. 127, § 48B (a). Notably, the Legislature also formed the Task Force on Emerging Adults in the Criminal Justice System (task force), which released a report in 2020 concluding that emerging adults "are a unique population that requires developmentally-tailored programming and services."22 Emerging Adults in the Massachusetts Criminal Justice System: Report of the Task Force on Emerging Adults in the Criminal Justice System (Feb. 26, 2020), 2020 Senate Doc. No. 2840, at 6. See St. 2018, c. 69, § 221. Massachusetts is not alone in recognizing that emerging adult offenders require different treatment from older adult offenders. For example, the District of Columbia now provides a 22 Noting that the dual sentencing scheme for youthful offenders under G. L. c. 119, § 58, applies only to juveniles, and that the task force's recommendations for emerging adults do not include offenders convicted of murder in the first degree, Justice Lowy's dissent concludes that neither demonstrates contemporary standards of decency here in the Commonwealth. Post at . See G. L. c. 119, § 74; Emerging Adults in the Massachusetts Criminal Justice System: Report of the Task Force on Emerging Adults in the Criminal Justice System (Feb. 26, 2020), 2020 Senate Doc. No. 2840, at 10. To the contrary, both examples demonstrate that the Legislature and other community members recognize that emerging adult offenders benefit from being treated differently from older adult offenders. Cf. Thompson v. Oklahoma, 487 U.S. 815, 823 (1988) (distinct treatment of younger juveniles compared to older juveniles "in criminal sanctions and rehabilitation" is evidence of contemporary standards of decency [citation omitted]). 27 chance at sentence reduction for people who were under twenty- five years old when they committed a crime. D.C. Code § 24- 403.03. In 2019, Illinois enacted a law allowing parole review at ten or twenty years into a sentence for most crimes, exclusive of sentences to life without parole, if the individual was under twenty-one years old at the time of the offense. 730 Ill. Comp. Stat. 5/5-4.5-115. Effective January 1, 2024, Illinois also ended life without parole for most individuals under twenty-one years old, allowing review after they serve forty years. Ill. Pub. L. No. 102-1128, § 5 (2022). California has extended youth offender parole eligibility to individuals who committed offenses before twenty-five years of age. Cal. Penal Code § 3051. Similarly, in 2021, Colorado expanded specialized program eligibility, usually reserved for juveniles, to adults who were under twenty-one when they committed a felony. Colo. House Bill No. 21-1209 (2021) (enacted). In Wyoming, "youthful offender" programs were revised to offer reduced and alternative sentencing for those under thirty years old. Wyo. Stat. Ann. §§ 7-13-1002, 7-13-1003. Legislation outside of the penological context is also instructive in ascertaining contemporary standards of decency. In Thompson, 487 U.S. at 838, the Supreme Court determined that the death penalty was unconstitutional when imposed on a fifteen year old offender based, in part, on then-current nonpenological 28 State statutes that treated younger juveniles differently from those closer to age eighteen. Among other things, the Court noted that "in all but one State a [fifteen]-year-old may not drive without parental consent, and in all but four States a [fifteen]-year-old may not marry without parental consent" (footnote omitted). See id. at 824-825. Similarly, Massachusetts, like most States, distinguishes emerging adults from older adults on a range of issues, granting rights and imposing responsibilities in a graduated manner. For example, one must be eighteen years of age to enter binding and enforceable contracts, to sit on a jury, to purchase lottery tickets, and to drive a common carrier motor vehicle.23 See G. L. c. 231, § 85O; G. L. c. 234A, § 4; G. L. c. 10, § 29; G. L. c. 159A, § 9. However, one must be twenty-one years of age to purchase and sell alcoholic beverages, to purchase tobacco products, to obtain a license to carry a handgun, to be a police officer, and to gamble. See G. L. c. 138, § 34; G. L. c. 270, § 6; G. L. c. 140, § 131 (d) (iv); G. L. c. 31, § 58; G. L. c. 22C, § 10; G. L. c. 23K, §§ 25 (h), 43. These statutes reflect the commonly held view that emerging adults generally 23Moreover, young adults who have reached eighteen years of age may "continue to be considered 'minors'" for purposes of parental support. Eccleston v. Bankosky, 438 Mass. 428, 429 (2003), quoting Stolk v. Stolk, 31 Mass. App. Ct. 903, 904-905 (1991). See G. L. c. 208, § 28. 29 are not equipped to assume all the responsibilities of adulthood, especially with respect to high risk activities. Cf. Thompson, 487 U.S. at 824-825. We are not the first State Supreme Court to appreciate the distinct ways in which our laws bear on emerging adults. Recently, the high courts in Washington and Michigan prohibited the mandatory imposition of life without the possibility of parole for those who are from eighteen to twenty years of age, and for those who are eighteen years of age, respectively. In Matter of the Personal Restraint of Monschke, 197 Wash. 2d 305 (2021), the Supreme Court of Washington considered evolving standards of decency, updated brain science, and precedent to conclude that mandatory sentences of life without parole violate the Washington Constitution when meted out to those under twenty-one when they committed the crime. See id. at 325-326. One year later, the Supreme Court of Michigan looked at the issue as it pertained to eighteen year old offenders. The court reasoned that because "the Eighth Amendment dictates that youth matters in sentencing," and because brain science has demonstrated that eighteen year old individuals possess the same attributes of youth as do juveniles, mandatorily subjecting an eighteen year old defendant to life in prison is "unusually excessive imprisonment and thus a disproportionate sentence that constitutes 'cruel or unusual punishment' under [the Michigan 30 Constitution]." People v. Parks, 510 Mich. 225, 234, 255 (2022).24 Twenty-two States and the District of Columbia do not mandate life without parole in any circumstance.25 Of the remaining twenty-eight States, only twelve (including Massachusetts) mandate life without parole.26 Moreover, the 24However, both the Washington and Michigan courts determined that a sentence of life without the possibility of parole could be imposed on young adult offenders after an individualized sentencing hearing to consider the offender's youth. See Parks, 510 Mich. at 240-241; Matter of the Personal Restraint of Monschke, 197 Wash. 2d at 327-328. 25In those twenty-two States and the District of Columbia, the highest penalties are imposed only on discretionary bases. See Alaska Stat. § 12.55.125; D.C. Code § 22-2104; Ga. Code Ann. § 16-5-1; Idaho Code Ann. §§ 18-4004, 19-2515; 720 Ill. Comp. Stat. 5/9-1; Ind. Code §§ 35-50-2-3, 35-50-2-9; Ky. Rev. Stat. Ann. § 532.030; Me. Rev. Stat. tit. 17-A, § 1603; Md. Code Ann., Crim. Law §§ 2-201, 2-203; Mont. Code Ann. § 45-5-102(2); Nev. Rev. Stat. § 200.030(4)(a)-(b); N.M. Stat. Ann. § 31-18-13; N.Y. Penal Law §§ 60.06, 70.00(5); N.D. Cent. Code § 12.1-32-01; Ohio Rev. Code Ann. §§ 2929.02, 2929.04; Okla. Stat. tit. 21, § 701.9; Or. Rev. Stat. § 163.107; R.I. Gen. Laws §§ 11-23-2, 12-19.2-1 to 12-19.2-5; S.C. Code Ann. § 16-3-20; Tenn. Code Ann. § 39-13-204; Utah Code Ann. § 76-5-203; Wis. Stat. § 973.014(1g)(c)-(2); Wyo. Stat. Ann. § 6-2-101. 26See G. L. c. 265, § 2 (a) ("any person who is found guilty of murder in the first degree shall be punished by imprisonment in the state prison for life and shall not be eligible for parole pursuant to [G. L. c. 127, § 133A"); Colo. Rev. Stat. § 18-1.3-401(1)(a)(V)(F), (4)(a)(I)-(II) ("A person . . . shall be punished by life imprisonment" without possibility of parole); Del. Code Ann. tit. 11, § 4209 ("Any person who is convicted of first-degree murder for an offense that was committed after the person had reached [his or her] eighteenth birthday shall be punished by . . . imprisonment for the remainder of the person's natural life without benefit of probation or parole or any other reduction"); Haw. Rev. Stat. 31 statutes in at least two of those States provide an opportunity to avoid the mandatory nature of the sentence.27 Twelve States mandate life without parole as an alternative to a discretionary death sentence,28 and five States only mandate life without § 706-656 ("Persons eighteen years of age or over at the time of the offense who are convicted of first degree murder or first degree attempted murder shall be sentenced to life imprisonment without the possibility of parole"); Iowa Code § 902.1 (on conviction of murder in first degree, "the court shall . . . commit the defendant . . . for the rest of the defendant's life . . . [and the defendant] shall not be released on parole unless the governor commutes the sentence to a term of years"); Mich. Comp. Laws § 750.316 (any person "who commits . . . first degree murder . . . shall be punished by imprisonment for life without eligibility for parole"); Minn. Stat. § 609.106 ("the court shall sentence a person to life imprisonment without possibility of release . . . [if] the person is convicted of first-degree murder"); N.H. Rev. Stat. Ann. § 630:1-a(III) ("A person convicted of a murder in the first degree shall be sentenced to life imprisonment and shall not be eligible for parole at any time"); 18 Pa. Cons. Stat. § 1102 ("a person who has been convicted of a murder of the first degree . . . shall be sentenced to . . . a term of life imprisonment"); Va. Code Ann. § 18.2-10(a) ("Any person who was [eighteen] years of age or older at the time of the offense and who is sentenced to imprisonment for life upon conviction of a Class 1 felony shall not be eligible for . . . parole"); Wash. Rev. Code § 10.95.030 (any person "convicted of the crime of aggravated first degree murder shall be sentenced to life imprisonment without possibility of release or parole"); W. Va. Code § 61-2-2 ("Murder of the first degree shall be punished by confinement in the penitentiary for life"). 27Iowa allows its Governor to commute the sentence to a term of years. Iowa Code § 902.2. Hawaii obligates the parole board to submit an application to its Governor to commute the sentence to one permitting parole after twenty years. Haw. Rev. Stat. § 706-656. 28See Ala. Code § 13a-6-2(c); Ariz. Rev. Stat. Ann. §§ 13- 751(A), 13-1105(D); Ark. Code Ann. § 5-10-101(c); Fla. Stat. § 775.082; Kan. Stat. Ann. § 21-6617 (for capital murder); La. 32 parole if aggravating circumstances exist.29 Massachusetts is one of only ten States that currently require eighteen through twenty year old individuals who are convicted of murder in the first degree to be sentenced to life without parole. We also may consider where other nations stand in this analysis. See Okoro, 471 Mass. at 61. See also Graham, 560 U.S. at 80 ("The judgments of other nations and the international community are not dispositive as to the meaning of the Eighth Amendment," but "[t]he Court has looked beyond our Nation's borders for support for its independent conclusion that a particular punishment is cruel and unusual"). The United Kingdom has banned life without parole for any offender under twenty-one years of age at the time of the offense. Sentencing Act 2020, c. 17, § 322, sch. 21, par. 2 (U.K.). And in 2022, the Supreme Court of Canada unanimously ruled that life without parole sentences were unconstitutional for all offenders, regardless of age. R. v. Bissonnette, 2022 SCC 23. The foregoing examples suggest that the "evolving standards of decency that mark the progress of a maturing society" referenced Rev. Stat. Ann. § 14:30(C); Miss. Code Ann. §§ 47-7-3(1)(d), 97- 3-21; Mo. Rev. Stat. § 565.020; Neb. Rev. Stat. § 28-105; N.C. Gen. Stat. § 14-17; S.D. Codified Laws § 22-6-1; Tex. Penal Code Ann. § 12.31. 29See Cal. Penal Code § 190.2; Conn. Gen. Stat. §§ 53a- 35a(1)(B), 53a-54b; N.J. Stat. Ann. § 2C:11-3; Va. Code Ann. §§ 18.2-10, 18.2-31; Vt. Stat. Ann. tit. 13, § 2303. 33 in Miller, 567 U.S. at 469, trend away from life without parole for emerging adults (citation omitted). 2. Life without parole for emerging adults violates art. 26. Our comprehensive review informs us that Supreme Court precedent, as well as our own, dictates that youthful characteristics must be considered in sentencing, that the brains of emerging adults are not fully developed and are more similar to those of juveniles than older adults, and that our contemporary standards of decency in the Commonwealth and elsewhere disfavor imposing the Commonwealth's harshest sentence on this cohort. Consequently, we conclude that a sentence of life without the possibility of parole for emerging adult offenders violates art. 26.30 See Diatchenko I, 466 Mass. at 670. 3. Remedy. Because we have determined that it is unconstitutional to sentence emerging adults to life without the possibility of parole, we invalidate those provisions of our The contemporary standards of decency that govern our 30 decision today do not suggest a societal consensus that those aged twenty-one and above should be treated differently from older adults. Thus, while we acknowledge that the scientific record in this case suggests that the unique attributes of youth may persist in young adults older than twenty-one, our art. 26 proportionality analysis does not rely on science alone. See Libby v. Commissioner of Correction, 385 Mass. 421, 435 (1982), quoting District Attorney for the Suffolk Dist. v. Watson, 381 Mass. 648, 661-662 (1980) ("Article 26, like the Eighth Amendment, bars punishments which are 'unacceptable under contemporary moral standards'"). 34 criminal code that deny the possibility of parole to this cohort. General Laws c. 265, § 2, which was amended after Diatchenko I was decided, sets forth the penalty for murder in the first degree, distinguishing between the penalties for adults and juveniles: "(a) Except as provided in subsection (b), any person who is found guilty of murder in the first degree shall be punished by imprisonment in the [S]tate prison for life and shall not be eligible for parole pursuant to [G. L. c. 127, § 133A]. "(b) Any person who is found guilty of murder in the first degree who committed the offense on or after the person's fourteenth birthday and before the person's eighteenth birthday shall be punished by imprisonment in the [S]tate prison for life and shall be eligible for parole after the term of years fixed by the court pursuant to [G. L. c. 279, § 24]." Although we hold that it is unconstitutional to sentence individuals from eighteen to twenty years of age to life without the possibility of parole, we must "as far as possible, . . . hold the remainder [of the statute] to be constitutional and valid, if the parts are capable of separation and are not so entwined that the Legislature could not have intended that the part otherwise valid should take effect without the invalid part." Diatchenko I, 466 Mass. at 672, quoting Boston Gas Co. v. Department of Pub. Utils., 387 Mass. 531, 540 (1982). See G. L. c. 4, § 6, Eleventh ("The provisions of any statute shall be deemed severable, and if any part of any statute shall be adjudged unconstitutional or invalid, such judgment shall not 35 affect other valid parts thereof").31 Here, because emerging adults do not fit within the exception described in G. L. c. 265, § 2 (b), we must invalidate that portion of G. L. c. 265, § 2 (a), that denies parole eligibility to those from eighteen to twenty years old. See Diatchenko I, supra at 673. Likewise, we also must invalidate that portion of the parole statute, G. L. c. 127, § 133A, that denies parole to those from eighteen to twenty years of age.32 Because the Legislature does not currently provide a parole eligibility scheme for this category of offenders, we look to the next-most severe sentence under the sentencing scheme to determine the floor of parole eligibility. See Watt, 484 Mass. at 753-754, citing Diatchenko I, 466 Mass. at 672-673. For emerging adults convicted of murder in the first degree on or 31Notably, the Legislature specifically provides for the severability of G. L. c. 265, § 2. See St. 1982, c. 554, § 7 ("If any of the provisions of [G. L. c. 265, § 2,] or the application thereof to any person or circumstances is held invalid, such invalidity shall not affect other provisions or applications of this act which can be given effect without the invalid provisions or applications, and to this end the provisions of this act are declared severable"). 32 General Laws c. 127, § 133A, states in relevant part: "Every prisoner who is serving a sentence for life in a correctional institution of the commonwealth, . . . except prisoners serving a life sentence for murder in the first degree who had attained the age of [eighteen] years at the time of the murder . . . shall be eligible for parole at the expiration of the minimum term fixed by the court under [G. L. c. 279, § 24]." 36 after today's decision, that means applying G. L. c. 279, § 24, as amended through St. 2014, c. 189, § 6, which sets parole eligibility for juvenile offenders who have committed murder in the first degree: "In the case of a sentence of life imprisonment for murder in the first degree committed by a [juvenile], the court shall fix a minimum term of not less than [twenty] years nor more than [thirty] years; provided, however, that in the case of a sentence of life imprisonment for murder in the first degree with extreme atrocity or cruelty committed by a [juvenile], the court shall fix a minimum term of [thirty] years; and provided further, that in the case of a sentence of life imprisonment for murder in the first degree with deliberately premeditated malice aforethought committed by a [juvenile], the court shall fix a minimum term of not less than [twenty-five] years nor more than [thirty] years." However, the defendant in this case was sentenced to life without the possibility of parole pursuant to G. L. c. 265, § 2 (a), prior to the enactment of the aforementioned legislative changes in 2014, post-Diatchenko I. Therefore, this defendant and other emerging adults sentenced to life without the possibility of parole prior to July 25, 2014, may only be resentenced to the constitutionally permissible penalty available at that time -- life with the possibility of parole after fifteen years. See Commonwealth v. Costa, 472 Mass. 139, 146 (2015) (resentencing limited to available statutory penalty in effect at time of conviction). By providing an opportunity for parole, we do not diminish the severity of the crime of murder in the first degree because 37 it was committed by an emerging adult. Likewise, our decision today "should not be construed" to suggest that emerging adults receiving the benefit of resentencing under today's holding "should be paroled once they have served a statutorily designated portion of their sentences." Diatchenko I, 466 Mass. at 674. However, as we stated in Diatchenko I, we must recognize the "unique characteristics" of emerging adults that render them "constitutionally different" from adults for purposes of sentencing. Id., citing Miller, 567 U.S. at 471. As such, they must be granted a "meaningful opportunity to obtain release based on demonstrated maturity and rehabilitation" before the Massachusetts parole board, who will "evaluate the circumstances surrounding the commission of the crime, including the age of the offender, together with all relevant information pertaining to the offender's character and actions during the intervening years since conviction." Diatchenko I, supra, quoting Graham, 560 U.S. at 75. Conclusion. We remand this matter to the Superior Court for resentencing consistent with this opinion. So ordered. KAFKER, J. (concurring). I concur with the court's comprehensive review of the expert testimony, the judge's fact finding, and the applicable law. I write separately to emphasize in particular that the letter and spirit of our trailblazing decision in Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 655, 669 (2013) (Diatchenko I), S.C., 471 Mass. 12 (2015) (Diatchenko II), directs us to reach the same conclusion today that we reached a decade ago and extend those very same protections to the age group at issue -- eighteen through twenty year olds. In our landmark decision in Diatchenko I, we relied on the best science available at the time, legislative recognition of the legal differences between juveniles and adults in other contexts, and the special protections of art. 26 of the Massachusetts Declaration of Rights to declare that the Legislature's imposition of life sentences without the possibility of parole for juveniles was unconstitutional, because juveniles are less culpable than adults and more capable of change. We also employed distinctive reasoning that I discuss in some detail infra. In so doing, we provided greater protections for juveniles under art. 26 than the United States Supreme Court had under the Eighth Amendment to the United States Constitution, precluding not only mandatory life sentences without the possibility of parole but also 2 discretionary sentences of life without the possibility of parole. In the instant case, we are presented with comprehensive fact finding evaluating further advancements in developmental cognitive neuroscience and developmental psychology,1 demonstrating that eighteen through twenty year olds share the same characteristics that distinguished juveniles from adults in Diatchenko I and that rendered them less culpable and more capable of change. The extensive briefing also demonstrates legislative recognition that eighteen through twenty year olds similarly require differential treatment from those twenty-one and older in other relevant and related contexts. Indeed, when this age group has been recognized by the Legislature to require differential treatment, the legal rights in question implicate those same distinctive characteristics. Due to this convergence of science and law, I conclude that art. 26 precludes both mandatory and discretionary life 1 As one of the experts testified, the fields of developmental cognitive neuroscience and developmental psychology work in tandem with one another. "Cognitive neuroscience is the study of the brain and the cognitive operations . . . the brain supports, including thinking and decision-making," or "higher cognitive tasks or operation[s]," while the "developmental component" refers "to the study of the brain as it develops over time and across the lifespan." Comparatively, "developmental . . . psychology is concerned with behavior," and often "the research studies that are conducted in developmental neuroscience are first informed by behaviors that are observed in studies of development[al] psychology." 3 sentences without the possibility of parole for those who are older than eighteen but younger than twenty-one at the time they committed murder in the first degree. Thus, after serving from twenty-five to thirty years in prison as now prescribed by the Legislature for juvenile murderers, these eighteen through twenty year olds likewise shall have the possibility of convincing the parole board that they have redeemed themselves in prison, have taken responsibility for the terrible deaths that they caused in their youth, and deserve to be paroled.2 1. Discussion. a. Diatchenko, differentiating characteristics, and State constitutional law. Our reasoning in Diatchenko I built on the foundation of the United States Supreme Court's Eighth Amendment analysis in Miller v. Alabama, 567 U.S. 460 (2012), particularly "three significant characteristics differentiating juveniles from adult offenders." Diatchenko I, 466 Mass. at 660. "First, children demonstrate a lack of maturity and an underdeveloped sense of responsibility, leading to recklessness, impulsivity, and heedless risk-taking. Second, children are more vulnerable to negative influences and outside pressures, including from their family and peers . . . . Finally, a child's character is not as well formed as an adult's; his traits are less fixed and his 2 I note that the defendant here was convicted prior to the passage of the 2014 legislation that required from twenty-five to thirty years before parole eligibility, and thus is eligible for consideration for parole, as this court explained in Diatchenko I, after fifteen years in prison. See Diatchenko I, 466 Mass. at 673-674 (explaining reasons for fifteen year parole eligibility date at time). 4 actions less likely to be evidence of irretrievable depravity." (Quotations, citations, and alterations omitted.) Id. Together, these characteristics demonstrated that juveniles possessed "diminished culpability" and a "heightened capacity for change." Cf. id. at 661, quoting Miller, supra at 479. Recognizing these differences and "[a]n ever-growing body of research in developmental psychology and neuroscience [that] continues to confirm and strengthen the Court's conclusions," Miller, supra at 472 n.5, the Supreme Court concluded that a mandatory imposition of a sentence of life without the possibility of parole for juveniles was cruel and unusual in violation of the Eighth Amendment, id. at 479. The Court did, however, allow a discretionary imposition of this sentence based on an individualized hearing, requiring judges to consider "how children are different, and how those differences counsel against irrevocably sentencing them to a lifetime in prison." Id. at 480. We then took a significant additional step in Diatchenko I, 466 Mass. at 670-671, and went well beyond the Supreme Court's Eighth Amendment protections, concluding that the greater protection afforded by art. 26 also prohibited the discretionary imposition of life without parole for juveniles convicted of murder in the first degree. We determined, consistent with the scientific evidence presented, that "a conclusive showing of 5 traits such as an 'irretrievably depraved character,' . . . can never be made, with integrity, by the Commonwealth at an individualized hearing to determine whether a sentence of life without parole should be imposed on a juvenile homicide offender." Id. at 669-670, quoting Roper v. Simmons, 543 U.S. 551, 570 (2005). More specifically, we held that because "the brain of a juvenile is not fully developed, either structurally or functionally, by the age of eighteen, a judge cannot find with confidence that a particular offender, at that point in time, is irretrievably depraved." Diatchenko I, supra at 670. Thus, we concluded that our State Constitution prohibited trial judges from attempting to make individualized findings that were impossible to make reliably at the time of sentencing, and so we imposed a categorical ban on the imposition of this sentence for juveniles. Id. at 669-670. As the Superior Court judge comprehensively found and as the court explains in its opinion, the scientific evidence here demonstrates that the same three characteristics that distinguished juveniles from adults in Diatchenko I, 466 Mass. at 669-670, distinguish eighteen through twenty year olds in essentially the same way. No one disputes those findings or the 6 science on which they are based, including the authors of the dissenting opinions written in the instant case.3 I therefore emphasize that, based on the fact findings here, we cannot distinguish in any way this case from Diatchenko I on scientific grounds. That science was also, as explained ante, a significant factor in the decision in Diatchenko I, 466 Mass. at 669-670, helping to convince this court to provide greater protection under the State Constitution than the Supreme Court provided under the Federal Constitution when the Supreme Court's allowance of discretionary life without parole sentences for juveniles who committed murder in the first degree could not be reconciled with the science. Evolving science helps inform evolving standards of decency. Cf. Helling v. McKinney, 509 U.S. 25, 36 (1993) (regarding prison conditions, Eighth Amendment analysis requires both "scientific and statistical inquiry into the seriousness of the potential harm" and "assess[ment] whether society considers the risk . . . to be so 3 On remand, the judge heard expert testimony and oral argument and accepted an additional exhibit in evidence, before issuing findings of fact and conclusions of law on whether mandatory life without parole sentences for eighteen through twenty year old offenders violates art. 26. Neither party disputes his factual findings. Among those findings, the judge clarified that his findings were limited to those up to age twenty-one because, while one expert, Dr. Adriana Galván, included twenty-one year olds in her developmental cognitive neuroscience research, another expert, Dr. Laurence Steinberg, did not include them in his developmental psychology research. 7 grave that it violates contemporary standards of decency"). We particularly were concerned that trial judges would be required to make findings that the science demonstrated were not possible. Diatchenko I, supra. See the amicus brief submitted by twenty-three retired Massachusetts judges and others, at 36- 40.4 The Supreme Court has, over the vigorous dissent of the 4 author of Miller and two other Justices, since held that, for the individualized hearings required by the Eighth Amendment, "a finding of fact regarding a child's incorrigibility is not required" (quotation, citation, and alteration omitted). Jones v. Mississippi, 141 S. Ct. 1307, 1314-1315 (2021), quoting Montgomery v. Louisiana, 577 U.S. 190, 211 (2016). That the Supreme Court does not now require an explicit finding on incorrigibility under its line of Eighth Amendment cases does not change our previous determination under art. 26 that such a finding is necessary to justify a sentence of life without parole for those under eighteen because our State constitutional protections are greater than those of the Eighth Amendment. See Diatchenko I, 466 Mass. at 670. Nor is our determination in Diatchenko I inconsistent with our decision in Commonwealth v. Perez, 477 Mass. 677, 679 (2017) (Perez I), S.C., 480 Mass. 562 (2018) (Perez II), which required an individualized hearing "where a juvenile is sentenced for a nonmurder offense or offenses and the aggregate time to be served prior to parole eligibility exceeds that applicable to a juvenile convicted of murder." That hearing is different from the individualized hearing that we concluded was not possible in Diatchenko I, 466 Mass. at 669-670, because the hearing required by Perez I does not concern whether parole eligibility is necessary, as all juvenile offenders are entitled to parole eligibility after Diatchenko I. See Perez II, supra at 569. Rather, it asks judges to consider the permissibility of a longer term of imprisonment prior to parole eligibility for nonmurder offenses than for murder in the first degree. See Perez I, supra; Perez II, supra. Our decision in Perez I, supra at 686, also established a presumption against such longer parole eligibility sentences under art. 26 and therefore set a 8 Other important aspects of Diatchenko I also should apply equally here. We emphasized, for example, that life sentences without the possibility of parole were deemed particularly severe for those required to stay in prison from youth to death; indeed, we went so far as to compare such sentences to the death penalty, which we already had deemed "unconstitutional under art. 26." See Diatchenko I, 466 Mass. at 670 (describing life sentences without possibility of parole for juveniles as being "strikingly similar" to death penalty). That same reasoning applies to eighteen through twenty year olds, who likewise are fated to spend the vast majority of their lives in prison with no hope of release at any time. If this case is to be distinguished from Diatchenko I, it must therefore be on other grounds, each of which I address and reject infra, turning once again to Diatchenko I for guidance. b. The Legislature's right to define the punishment for the crime and distinguish juveniles from adult offenders. Justices Lowy and Cypher in their dissents emphasize that great deference is owed to the Legislature's right to define the punishment for criminal behavior and define the line between juvenile and adult offenders. See post at , (Lowy, J., dissenting); post at (Cypher, J., dissenting). As a general very high bar to justify them, which we confirmed and clarified in Perez II, supra at 571-573. 9 principle, I wholeheartedly agree with these propositions. But in Diatchenko I, we did not defer to the punishment established by the Legislature or to the line drawing (or, in that case, the absence of line drawing) between juveniles and adults. Rather, we concluded that the punishment, without necessary line drawing, was unconstitutional. Diatchenko I, 466 Mass. at 658- 659. In sum, we did not defer to the Legislature; we concluded that it acted unconstitutionally. Unlike the Supreme Court in its line of cases regarding acceptable criminal punishments for juveniles under the Eighth Amendment, we also did not define explicitly a fixed constitutional line for life sentences without the possibility of parole when we decided Diatchenko I. Compare Roper, 543 U.S. at 574 ("The age of [eighteen] is the point where society draws the line for many purposes between childhood and adulthood. It is, we conclude, the age at which the line for death eligibility ought to rest" [emphasis added]), with Diatchenko I, 466 Mass. at 669-670 (relying on "current scientific research on adolescent brain development" to reach conclusion that "the judge cannot ascertain, with any reasonable degree of certainty, whether imposition of this most severe punishment is warranted"). In defining that line previously in the death penalty context, the Supreme Court also recognized that it had itself recently set that line at sixteen and then moved it. 10 Roper, supra at 561-562. Perhaps recognizing that this line was not fixed for all purposes and might too be a moving target for sentences of life without the possibility of parole, we did not attempt such analysis or decide that it was applicable regardless of the science. Instead, we only answered what we were asked: whether it was constitutional to sentence "juveniles" to life without the possibility of parole as the Legislature provided, and we concluded that it was not, because the science demonstrated that juveniles were less culpable and capable of change. Diatchenko I, supra at 671. We then referenced and relied on a statutory definition of "juvenile" to define the scope of our holding at the time. Id. at 659 n.8, 673 n.17.5 The question then becomes whether there is a meaningful constitutional difference between overruling the Legislature's decision that it is permissible to sentence juveniles to life in prison without the possibility of parole and overruling the Legislature's decision that it is permissible to sentence eighteen through twenty year olds to life in prison without the possibility of parole, when the fact finding regarding the 5 I do not in any way seek to redefine eighteen through twenty year olds as juveniles. Rather, I consider eighteen through twenty year olds as a distinct legal category as explained infra, as the Legislature itself has done in a variety of contexts. 11 scientific evidence now conclusively demonstrates that eighteen through twenty year olds, just like juveniles, are less culpable for their crimes and more capable of change than adults. Justices Lowy and Cypher find such a basis in deference to the Legislature: we should defer to the Legislature because it did not exclude eighteen to twenty year olds from a statute that provides for life sentences without the possibility of parole for murder in the first degree. See post at , (Lowy, J., dissenting); post at (Cypher, J., dissenting). The same, however, was true for juveniles when we decided Diatchenko I, 466 Mass. at 672-673. Although the Legislature at that time authorized life sentences without the possibility of parole for juveniles, as explained supra, we found such punishment unconstitutional. Id. Justices Lowy and Cypher in their dissents also state that we should defer to the Legislature because it has defined eighteen as a fixed line between juveniles and adults.6 I 6 Justice Cypher posits that the extension of rights to those over the age of eighteen has always been granted first by the Legislature and not the courts, and so we would be the first to define protections for a certain category of individuals based on an age group of our definition. Post at (Cypher, J., dissenting). The latter consideration ignores, however, the evolution of Federal juvenile death penalty jurisprudence, which involved judicial line drawing based on age without reliance on a clearly legislatively defined age group. In Thompson v. Oklahoma, 487 U.S. 815, 823, 838 (1988), a plurality of the Supreme Court prohibited the imposition of the death penalty for those under the age of sixteen at the time they committed their 12 conclude, as does the court, that the legislative line drawing is more nuanced. The Legislature does not uniformly provide eighteen through twenty year olds with the full benefits and responsibilities of those twenty-one and older. Rather, the Legislature recognizes that eighteen, nineteen, and twenty year olds fall into a distinct category requiring special consideration; they are permitted certain legal rights but not others. See State House News Service (Sen. Sess.), June 28, 2018 (statement of Sen. Jason Lewis, chair of Joint Committee on Public Health) (regarding tobacco purchasing age limit, "there really is no single age of adulthood in our society"; [w]e make decision[s] on a case-by-case basis depending on the activity"). For example, they are entitled to vote, serve on a jury or in the military, and drive a car. See G. L. c. 51, § 1 (voting); G. L. c. 234A, § 4 (jury); G. L. c. 90, § 8 (driving). See also Requirements to enlist in the U.S. military, USA.gov, offense. This decision stood in contrast to the many ways in which the age of eighteen stood as a demarcation between juveniles and adults. The Court in Thompson, 487 U.S. at 838, had been asked to "'draw a line' that would prohibit the execution of any person who was under the age of [eighteen] at the time of the offense." The Court limited its decision, however, to "the case before" it and so drew the line at sixteen. In 2005, in Roper, 543 U.S. at 570-571, the Court took the opportunity to extend Thompson to protect all juveniles -- those up to age eighteen -- from the imposition of the death penalty. In both instances, the judiciary -- not the Legislature -- extended these protections. For us to do the same would not, therefore, be unprecedented. 13 https://www.usa.gov/military-requirements [https://perma.cc/Y9MG-HWG4] (beginning at age seventeen). But they cannot purchase and sell alcohol or tobacco, serve as a State police officer, gamble, or even supervise drivers with learner's permits. See G. L. c. 138, § 34 (alcohol); G. L. c. 270, § 6 (tobacco); G. L. c. 31, § 58 (municipal police officer); G. L. c. 22C, § 10 (State police officer); G. L. c. 23K, § 43 (gambling); G. L. c. 90, § 8B (learner's permits). They are also excluded from purchasing marijuana by a ballot initiative, demonstrating that the public recognizes a similar distinction. G. L. c. 94G, § 7 (a). Their rights regarding firearms are also more limited than those twenty-one and over. G. L. c. 140, § 131 (d) (iv) (license to carry large capacity firearm restricted to those twenty-one and over). I thus emphasize that legal rights from which eighteen through twenty year olds are excluded appear to implicate and reflect a legislative concern about the very characteristics that are at issue in this case: "a lack of maturity and an underdeveloped sense of responsibility, leading to recklessness, impulsivity, and heedless risk-taking" and a greater "vulnerab[ility] . . . to negative influences and outside pressures, including from their family and peers" (quotations and citations omitted). Diatchenko I, 466 Mass. at 660. Senator Patricia Jehlen, the author of an amendment to the 14 expanded gaming bill that prohibited marketing to individuals under twenty-one, stated: "The bill itself says that casinos may not allow people under the age of [twenty-one]. . . . Current Massachusetts law says you can't buy alcohol if you're under [twenty-one]. I think that these are consistent that people's brains have not matured by the time they're [eighteen]." State House News Service (Sen. Sess.), Oct. 11, 2011. Likewise, the legislative history regarding increasing the age for tobacco consumption to twenty-one shows that the Legislature was concerned about the underdeveloped brains of young people, including those above eighteen. See State House News Service (Sen. Sess.), June 28, 2018 (statement of Sen. Jason Lewis) ("Our young people are particularly susceptible. . . . [Nicotine] has harmful health impacts on the developing brain. . . . It helps [to] get tobacco products out of high school social networks"); Press Release, Senate Passes Jason Lewis Bill to Protect Youth from the Health Risks of Tobacco and Nicotine Addiction (June 30, 2018), https://senatorjasonlewis.com/2018/06/30/tobacco-21 [https://perma.cc/6MQM-QHXQ] (quoting Sen. President Harriette L. Chandler, "This legislation protects young adults whose minds and bodies are still developing . . ."). See also Governor's Legislative Files, House Bill No. 4218, "An Act increasing the minimum age for appointment as a police officer," Bill Summary 15 (2003) ("Advocates of this legislation suggest increasing the minimum age for appointment for the position of police officer will ensure that individuals taking on the responsibilities associated with modern policing posses[s] the requisite life skills and maturity").7 The criminal justice system also reflects special consideration for this age group, again reflecting the special characteristics of eighteen through twenty year olds. For example, the Legislature has authorized the Department of Youth Services to maintain custody of young people adjudicated to be youthful offenders up to age twenty-one. G. L. c. 119, § 58. Likewise, the Massachusetts Sentencing Guidelines have instructed judges to consider the developmental characteristics of eighteen through twenty year olds even when they have been tried as adults. The Legislature has also, in its recent comprehensive criminal justice reform, authorized the State and 7 Federal legislative history of the highway funding law that led Massachusetts to raise the drinking age to twenty-one discussed similar concerns. See Hearing before Subcommittee on Surface Transportation of the United States Senate Committee on Commerce, Science, and Transportation on Oversight of the National Highway Traffic Safety Administration (Sept. 13, 1983), reprinted in Legislative History of the Surface Transportation Assistance Act of 1982 Amendments (1984) (statement of Robert S. Vinetz, M.D.) (younger drivers' high rate of motor vehicle accidents due to "especially deadly combination of being new and inexperienced drivers, of having the tendency toward increased risk-taking, of having an exaggerated belief in their own invulnerability and in experimenting with alcohol and drugs"). 16 county prison systems to "establish young adult correctional units" with "targeted interventions, age appropriate programming[,] and a greater degree of individual attention" for those within this age group and also extended such consideration to those as old as twenty-four, G. L. c. 127, § 48B. In sum, the Legislature has recognized that eighteen through twenty year olds are a distinct category requiring special consideration, at least regarding legal rights that implicate risky, impulsive, and potentially dangerous behavior and peer pressure -- the very characteristics at issue in this case. Given this legislative recognition of the need for differential treatment of eighteen through twenty year olds in such contexts, and the science and fact finding in this case, which equates eighteen through twenty year olds to juveniles on the relevant three characteristics that rendered juveniles less culpable for their crimes, more capable of change, and thus entitled to the possibility of parole in Diatchenko I, 466 Mass. at 660, I conclude that eighteen through twenty year olds should likewise be entitled to State constitutional protection from life sentences without the possibility of parole. As in Diatchenko I, we should not defer to the Legislature when it recognizes the distinctive characteristics of the eighteen through twenty year old defendants at issue and treats them differently from those twenty-one and over in many ways, but 17 then disregards those differences for our most severe criminal punishments. Upholding such sentences means that we disregard the best science and continue to impose the most severe penalty on a distinct legal category of individuals that we know are less culpable and more capable of change.8 For all these reasons, this court in Diatchenko I, 466 Mass. at 671, declared the statute unconstitutional as applied to a certain age group. Deference to the Legislature's determination of a punishment that we, in Diatchenko, analogized to the death penalty is different from ordinary deference. To determine whether such a punishment is cruel or unusual is a critical function of this court, and one that the court has exercised with particular vigilance despite the objections of dissenting justices calling for greater deference to the Legislature. See id. at 672. See also, e.g., Commonwealth v. Colon-Cruz, 393 Mass. 150, 181 (1984) (Wilkins, J., dissenting); 8 I also concur with the court's decision to limit this relief to those under twenty-one. Unlike eighteen to twenty year olds, those twenty-one and over have been considered by the Legislature to have the full benefits and responsibilities of adults. I consider the Legislature's recognition of the need for differential treatment of those eighteen to twenty in a variety of other contexts when the legal rights in question implicate the same distinctive characteristics at issue in this case to be an important component of the analysis. That legislative recognition is absent when we consider those twenty- one and over. It is the convergence of law and science, not just science alone, that governs the art. 26 analysis here. 18 id. (Nolan, J., dissenting); District Attorney for Suffolk Dist. v. Watson, 381 Mass. 648, 687 (1980) (Quirico, J., dissenting).9 c. The role of the tripartite analysis in Diatchenko I. Another exceptional aspect of the Diatchenko I decision is the legal authority to which this court turned for guidance and support. We did not expressly employ the tripartite analysis from Commonwealth v. Jackson, 369 Mass. 904, 910, 913 (1976), and Cepulonis v. Commonwealth, 384 Mass. 495, 497-498 (1981) (considering "the penalties prescribed for the same offense in other jurisdictions"), and therefore tie our decision to how most other States treated like offenders by applying the third step of that analysis. We did not even compare ourselves to other States or express concern that we were providing greater protection than those other States. Again, this is a critical and distinctive aspect of Diatchenko I. Instead, relying on our own State Constitution, a legislatively defined category, which in that case was juveniles, and comprehensive fact finding grounded in science, to ensure the objectivity and integrity of our decision-making process, we broke new ground in this landmark decision, like other seminal State constitutional 9 The deference recommended here has similarities to those dissents. See, e.g., Colon-Cruz, 393 Mass. at 184-185 (Nolan, J., dissenting). It is important to remember that Diatchenko I, 466 Mass. at 670, made the comparison between life without the possibility of parole and the death penalty. This is another critical aspect of Diatchenko I that we cannot ignore. 19 decisions we have issued.10 Compare Goodridge v. Department of Pub. Health, 440 Mass. 309, 312, 339 n.31 (2003) (recognizing that "our decision marks a change in the history of our marriage law" while noting only three other States' courts had taken affirmative steps to recognize same-sex marriage under their Constitutions while Federal government had not); Watson, 381 Mass. at 650, 662 (striking down death penalty for violating art. 26 because it was "unacceptably cruel under contemporary standards of decency" despite lack of "unanimity of public opinion" as it was "administered with unconstitutional arbitrariness and discrimination"). For further support when deciding Diatchenko I, 466 Mass. at 285 n.16, we turned to the author of our State Constitution, John Adams, and even widened our perspective internationally. We noted Adams's reminder that "we belong to an international community that tinkers toward a more perfect government by learning from the successes and failures of our own structures and those of other nations." Id., citing J. Adams, Preface, A Defence of the Constitutions of Government of the United States of America (1797). We also referenced the United Nations 10I note that Diatchenko I has been cited in 127 decisions, including fifty out-of-State cases. See Goldstein, One of One: Justice Gants and Lessons from the Keo Case, 62 B.C. L. Rev. 2827, 2828 (2021) (referring to Diatchenko I as "momentous decision[]"). 20 Convention of the Rights of the Child, which bans life in prison without parole for juveniles. Diatchenko I, supra. Given the distinct letter and spirit of Diatchenko I described in detail supra, and the undisputed factual findings here demonstrating that eighteen through twenty year olds share the same relevant characteristics regarding diminished culpability and heightened capacity for change as juveniles, I conclude that we should extend the very same protections provided to Gregory Diatchenko to eighteen through twenty year olds. I discern no basis for distinguishing them given the distinct reasoning developed in Diatchenko I. A sentence of life in prison without parole eligibility review for those up to age twenty-one -- individuals with diminished culpability and a heightened capacity for change -- is no less cruel or unusual than it is for those up to age eighteen. Cf. Diatchenko I, 466 Mass. at 670-671. Thus, we should have been "obliged to declare part of [this statute] unconstitutional," id. at 672, and have provided these eighteen through twenty year old homicide offenders with "a meaningful opportunity for release on parole," should they "demonstrate[] maturity and rehabilitation," so that their "life sentence [is] constitutionally proportionate," Diatchenko II, 471 Mass. at 29-30. d. Limited remedy. We also, as in Diatchenko I, 466 Mass. at 671, need only hold a very specific application of the 21 statute unconstitutional. As we explained in Diatchenko I, "the unconstitutionality of this punishment arises not from the imposition of a sentence of life in prison, but from the absolute denial of any possibility of parole" for a class of offenders who a trial judge cannot reliably determine to be irretrievably depraved at the time of sentencing. See id. Once they have a chance to mature, however, that decision, as well as the other factors relevant to parole, would and should be made by a parole board. That decision would also be made after many years of imprisonment. See id. at 674. Under current law, those under age eighteen who are convicted of murder in the first degree are eligible for parole only after serving from twenty-five to thirty years for murder convicted with deliberate premeditation and thirty if the murder was committed with extreme atrocity or cruelty. G. L. c. 279, § 24. I would extend the same opportunity to those older than eighteen but under the age of twenty-one. Essentially, the legislative regime imposed for juvenile murderers would be extended to eighteen to twenty year olds without further changes in the statutory scheme. The possibility of such reformative change after a lengthy period of incarceration has also been demonstrated since we decided Diatchenko I. Of the juvenile offenders who were serving mandatory life sentences without parole at the time of 22 the Diatchenko I decision and have since received parole hearings, seventy-four percent have been granted parole. As Diatchenko I and its aftermath have demonstrated, the possibility of redemption exists for the young, even those who have committed the most horrible crimes, after they have spent many years in prison maturing and taking responsibility for the terrible deaths that they caused in their youth. For all these reasons, I conclude that a sentence of life without the possibility of parole for eighteen through twenty year olds constitutes cruel or unusual punishment under art. 26 of our Declaration of Rights. That applies to both discretionary as well as mandatory life sentences without the possibility of parole for those eighteen through twenty years of age. WENDLANDT, J. (concurring, with whom Gaziano, J., joins). The determination whether the Commonwealth's harshest punishment is so disproportionate to the offender as to shock the conscious is neither one we abdicate to the Legislature, as marshalled by the dissent, nor one we rest on the shoulders of scientists and social scientists. I write to clarify what should be pellucid: it is our constitutional duty to ensure prescribed punishments pass constitutional muster, and nothing in art. 30 of the Massachusetts Declaration of Rights prevents us from doing so. To be faithful to the enormity of this charge, we must undertake a comprehensive review of our statutes, the scientific record, our collective experiences, and common sense. Having examined these sources, I conclude that they confirm what any parent of adult children can tell you: a child does not go to bed on the eve of her eighteenth birthday and awaken characterized by a lessened "transient rashness, proclivity for risk, and inability to assess consequences." Miller v. Alabama, 567 U.S. 460, 472 (2012). In recognition of this indisputable fact, society does not treat the transition from childhood to adulthood as a binary act accomplished at age eighteen; becoming an adult is much more fluid, with development continuing long after a child's eighteenth birthday. In the ways that matter for the Commonwealth's harshest punishment, young adults of the ages of eighteen, nineteen, and twenty share key characteristics 2 with their under-eighteen year old peers; they "have diminished culpability and greater prospects for reform" than older adults and "are less deserving of the most severe punishments." See id. at 471, quoting Graham v. Florida, 560 U.S. 48, 68 (2010). For this reason, condemning a person in the process of "growing up" to die in prison on the basis that she falls on the "wrong" side of an arbitrary line drawn at age eighteen is inconsistent with "the evolving standards of decency that mark the progress of a maturing society" (citation omitted). Graham, supra at 58. Accordingly, I agree with the court that imposition of life without the possibility of parole on young adults ages eighteen, nineteen, and twenty is unconstitutional. 1. Legislature's treatment of young adults. Undoubtedly, the first source in the determination of our contemporary standards of decency that define the bounds of cruel punishment is legislative enactments. See Good v. Commissioner of Correction, 417 Mass. 329, 335 (1994) ("In divining contemporary standards of decency, we may look to State statutes and regulations, which reflect the public attitude as to what those standards are"). See also Graham, 560 U.S. at 61, quoting Roper v. Simmons, 543 U.S. 551, 563 (2005) ("The Court first considers 'objective indicia of society's standards, as expressed in legislative enactments and state practice' . . ."); Atkins v. Virginia, 536 U.S. 304, 312 (2002) ("the clearest and most 3 reliable objective evidence of contemporary values is the legislation enacted by the country's legislatures" [quotation and citation omitted]).1 Our statutes reflect legislative recognition that maturity is a gradual endeavor,2 and that while age eighteen is a milestone, society does not view it as the end of the metamorphosis toward adulthood. As the court and Justice Kafker thoroughly catalogue, for many activities considered by society to require greater care, less risk taking, and more resilience 1 In concluding that a mandatory sentence of life in prison without the possibility of parole violated the Eighth Amendment to the United States Constitution when imposed on juvenile nonhomicide offenders, the United States Supreme Court considered that, although thirty-seven State legislatures permitted the sentence, only eleven States imposed the sentence in practice, and vanishingly few juvenile offenders actually received it. See Graham, 560 U.S. at 62-67 (only approximately 123 juvenile nonhomicide offenders were serving sentences of life without parole; seventy-seven of those offenders were in Florida, and the remainder were in just ten States). See also Atkins, 536 U.S. at 316 (considering that "even in those States that allow the execution of [offenders with intellectual disabilities], the practice is uncommon," in concluding that "a national consensus has developed" against executing such individuals). Because the sentence is mandatory for all adults over the age of eighteen in Massachusetts, see G. L. c. 265, § 2 (a), we cannot look to sentencing practices as they pertain to young adult offenders. 2 As Justice Cypher notes, post at , at a point earlier than the age of eighteen, the Legislature has recognized that one commences the transition from being a child to being an adult and therefore awards certain freedoms to these young people before they turn eighteen years old. For example, young women, as early as age sixteen, can obtain an abortion without parental consent. See G. L. c. 112, § 12R. 4 to peer pressure, the Legislature continues to treat young adults over the age of eighteen like juveniles. To engage in these activities legally, young adults must wait until they are twenty-one. This special treatment exemplifies the Legislature's acknowledgment of two facts: first, that the impetuousness of youth, the proclivity to risk taking, and the susceptibility to peer pressure are not attributes exclusive to those under the age of eighteen, and instead continue into young adulthood; and second, that these attributes are not fixed, but generally fade over time because young adults, like juveniles, are characterized by a malleability of character.3 2. Science and social science. Of course, consideration of legislation is the beginning; it is not the end of our analysis under art. 26 of the Massachusetts Declaration of Rights. To be faithful to our responsibility to protect individuals from cruel or unusual punishment meted out by the 3 Private institutions also recognize that young adults are not ready for all the responsibilities of adulthood. See, e.g., K.U. Lindell & K.L. Goodjoint, Juvenile Law Center, Rethinking Justice for Emerging Adults: Spotlight on the Great Lakes Region, at 12 (2020) ("while not a statutory restriction, most car rental companies limit rentals to individuals under age [twenty-five], recognizing the increased risk posed by this age group"). See also Metz, How Age and Gender Affect Car Insurance Rates, Forbes Advisor (updated Aug. 17, 2023), https://www .forbes.com/advisor/car-insurance/rates-age-and-gender [https: //perma.cc/LB8G-PHEG] ("The high car insurance rates that young drivers pay start to go down at age [twenty-five]"). 5 State, we cannot be blind to the truths that the scientific sources with which we have been presented show.4 Our experiment with scientific fact finding on the topic of adult brain development validates the graduated treatment of young persons reflected in our statutes. The court's careful review of this record is undisputed. In brief, it shows that neuroscientists see in their magnetic resonance imaging (MRI) scans corroboration for that which we experience in life; the brain characteristics of persons even years older than eighteen mirror those of persons under eighteen. The brain generally continues to develop through the mid-twenties. Until some ill- defined point in the third decade of life, adults, especially 4 See, e.g., Miller, 567 U.S. at 471 (determination that life in prison without possibility of parole for juveniles violates Eighth Amendment rested "not only on common sense -- on what 'any parent knows' -- but on science and social science as well" [citation omitted]); Graham, 560 U.S. at 68 (considering "developments in psychology and brain science" in Eighth Amendment proportionality analysis as to life in prison without possibility of parole for juveniles convicted of nonhomicide offenses); Roper v. Simmons, 543 U.S. 551, 569 (2005) (considering what "any parent knows" and what "scientific and sociological studies . . . tend to confirm" to conclude death penalty for juveniles violates Eighth Amendment); Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 655, 669 (2013), S.C., 471 Mass. 12 (2015) (concluding imposition of sentence of life in prison without possibility of parole for juveniles, even after individualized hearing, violates art. 26 of Massachusetts Declaration of Rights "[g]iven current scientific research on adolescent brain development"). 6 men,5 generally are more impulsive and their brains are more plastic than those of older adults.6 3. Collective experience and common sense. Significantly, while the findings based on current technological advances in brain science show substantial similarities between juveniles and young adults, we do not check our common sense at the laboratory door. Our statutes, experiences, and common sense tell us that there is no magic switch to the process of growing up, and that fact, now buttressed by neuroscientific data and informed by social science studies, must be weighed in the exercise of our duty to determine whether punishment is cruel or unusual. See Matter of the Personal Restraint of Monschke, 197 Wash. 2d 305, 306 (2021) ("Modern social science, our precedent, 5 See L. Brizendine, The Female Brain 44 (2006) (finding that female brain "matures two or three years earlier than the male brain"). See also Cauffman & Steinberg, (Im)maturity of Judgment in Adolescence: Why Adolescents May Be Less Culpable Than Adults, 18 Behav. Sci. & L. 741, 753 (2000) (finding that "females exhibit greater psychosocial maturity than males"). 6 Scientific studies report brain maturation at different ages: sometimes at the age of twenty-one, sometimes at twenty- two, sometimes at twenty-three or twenty-five, and sometimes in the middle to late twenties. Moreover, studies report that certain aspects of brain development, such as susceptibility to peer pressure and impulse control, also appear to mature at different rates. 7 and a long history of arbitrary line drawing have all shown that no clear line exists between childhood and adulthood").7 The scientific snapshot in this case confirms that which is apparent in our laws and in our treatment of this age cohort more generally –- namely, that in the ways that matter for criminal sentencing, young adults are similar to juveniles. Like juveniles, young adults have "an underdeveloped sense of responsibility, leading to recklessness, impulsivity, and heedless risk-taking"; they are more vulnerable to peer pressure; and their "character is not as well formed as an adult's . . . and [their] actions [are] less likely to be evidence of irretrievabl[e] deprav[ity]" (quotations omitted). Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 7 The parties in this case ask us to consider the constitutionality of the punishment of life in prison without the possibility of parole when it is imposed on defendants aged eighteen, nineteen, and twenty. That the scientific record is not precise as to where the line should be drawn, see note 6, supra, should come as no surprise given our collective experiences showing that, while some generalizations may be drawn, in the end "growing up" is an individualized endeavor. This does not mean that "we may as well give up and let the [L]egislature draw its arbitrary lines." Matter of the Personal Restraint of Monschke, 197 Wash. 2d at 323. At the least, in response to the only question with which we have been presented in this case, I conclude that drawing a fixed line at the age of eighteen, thereby leaving young adults aged eighteen, nineteen, and twenty to the punishment, is not supported by our statutes, the scientific data and social science, our collective experiences, or common sense. 8 655, 660 (2013) (Diatchenko I), S.C., 471 Mass. 12 (2015), quoting Miller, 567 U.S. at 471. Relying on these hallmarks of youth, the United States Supreme Court concluded that mandatory life in prison without the possibility of parole is a cruel punishment when applied to juveniles. Miller, 567 U.S. at 489. And, in view of these characteristics of juveniles, we separately concluded that art. 26 prohibits the mandatory imposition of this punishment. See Diatchenko I, 466 Mass. at 667. We also concluded that art. 26 offers greater protections to our children than are available under the Eighth Amendment to the United States Constitution. Specifically, we concluded that, in view of the hallmarks of youth that characterize juveniles, art. 26's greater protection prohibits so-called Miller hearings to determine whether, on an individualized consideration of a particular juvenile homicide defendant's circumstances, the sentence of life without the possibility of parole was proportionate. Id. at 669-671. Because the aforementioned review of our statutes, the scientific data, collective experiences, and common sense confirms that these same qualities characterize young adults, it necessarily follows that art. 26 prohibits the punishment as applied to this cohort. For these reasons, I concur. LOWY, J. (dissenting, with whom Cypher and Georges, JJ., join). I cannot say that society, through its elected officials, may not express its revulsion of the crime of murder in the first degree by imposing a punishment of life without the possibility of parole on adults without offending our Declaration of Rights. Therefore, I respectfully dissent. The power to "define a crime and ordain its punishment" is an exclusively legislative function, and "in judging legislative determinations of crimes and punishments, we exercise our powers of review with great caution" (citation omitted). Opinions of the Justices, 378 Mass. 822, 830 & n.7 (1979). For the crime of murder in the first degree, the Legislature has deemed the mandatory imposition of life without the possibility of parole to be the appropriate punishment for adults eighteen and older convicted of this offense. While we have an obligation to intervene when the Legislature acts unconstitutionally, unless the punishment the Legislature imposes is "so disproportionate" that it "shocks the conscience and offends fundamental notions of human dignity" (citation omitted), Cepulonis v. Commonwealth, 384 Mass. 495, 497 (1981), we must exercise restraint and uphold it, see art. 26 of the Massachusetts Declaration of Rights; Eighth Amendment to the United States Constitution. In this case, the defendant argues that, in light of recent advances in scientific brain research concerning young adults, 2 the line between those who may constitutionally be subject to the mandatory imposition of life without the possibility of parole and those who may not should be at the age of twenty-one, rather than at the age of eighteen. Our analysis for determining whether a punishment is constitutionally disproportionate considers whether the punishment is cruel or unusual in light of "contemporary standard[s] of decency" (citation omitted). Libby v. Commissioner of Correction, 385 Mass. 421, 431 (1982). We look to statutes enacted by the Legislature, along with regulations, as the best objective evidence for divining contemporary values. See Good v. Commissioner of Correction, 417 Mass. 329, 335 (1994). Doing so is not affording uncritical deference to the Legislature's choice of punishment, but rather it is a direct application of our constitutional doctrine that looks to legislation to derive contemporary values. Indeed, "legislatures, not courts, are constituted to respond to the will and consequently the moral values of the people." See Gregg v. Georgia, 428 U.S. 153, 175 (1976), quoting Furman v. Georgia, 408 U.S. 238, 383 (1972) (Burger, C.J., dissenting). Consequently, to determine whether this mandatory sentence violates art. 26, we must look to legislative evidence to determine whether the line that the defendant urges us to draw at the age of twenty-one is one that is consistent with society's contemporary values. 3 Contrary to the court's conclusion that it is, the objective sources of contemporary standards of decency in the Commonwealth simply do not reflect a public consensus that life without parole, when imposed mandatorily on individuals from eighteen to twenty who have been convicted of murder in the first degree, is cruel or unusual. Rather, the Legislature has definitively drawn the line between childhood and adulthood at eighteen, and objective indicia of contemporary standards of decency in the Commonwealth demonstrate support for, rather than objection to, treating individuals within this age range as adults in our criminal justice system when they commit the crime of murder in the first degree. Where individuals from eighteen to twenty-one have been deemed adults by the Legislature and society, precedent relating to the sentencing of juveniles -- who are "constitutionally different from adults for purposes of sentencing" -- is inapt. Miller v. Alabama, 567 U.S. 460, 471 (2012). Thus, our decision in Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 655, 669 (2013) (Diatchenko I), S.C., 471 Mass. 12 (2015), cannot resolve the question of the proportionality of the mandatory sentence challenged in this case. In Diatchenko I, we did not purport to draw a line between juveniles and adults. Our focus, rather, was on a category of individuals -- predefined by the Legislature -- and our inquiry as to that 4 category was precise and limited. See id. at 659 n.8. Where the United States Supreme Court concluded in Miller, supra at 469, that imposing mandatory life without parole on juveniles violates the Eighth Amendment, we were addressing only the discretionary imposition of such a sentence, i.e., whether, under art. 26, an individualized assessment of a juvenile offender could ever result in a determination that "a sentence of life without parole should be imposed on a juvenile homicide offender." Diatchenko I, supra at 670. We concluded that art. 26 did not permit such an individualized assessment at the time of sentencing. As it relates to the court's conclusion that this mandatory sentence is categorically unconstitutional, scientific brain research, untethered to societal views expressed through legislation, can neither draw the line between childhood and adulthood nor manufacture a new category of individuals entitled to distinct constitutional treatment for purposes of determining whether a sentence is constitutionally disproportionate under art. 26. And, even if it could, science does not definitively place the line of brain maturation at twenty-one, but rather suggests that it extends into the mid-twenties. Perhaps nothing speaks louder to the flaws in the court's holding that this mandatory sentence violates art. 26 than the court having crafted a line that ends at age twenty-one, thereby engaging in 5 legislative line drawing inconsistent with the science upon which it relies. Where punishment is involved, we must look to society and the Legislature to determine where the appropriate line is and where it should be. Our assessment under art. 26 is not whether the mandatory imposition of life without the possibility of parole for individuals from eighteen to twenty-one is, in our view, wise, prudent, or even best for society. Our inquiry is limited to whether the punishment, chosen by the Legislature, is so disproportionate that it reaches the level of cruel or unusual. See Diatchenko I, 466 Mass. at 669. Because, under our contemporary standards of decency and precedent, the mandatory imposition of life without the possibility of parole on adults who commit murder in the first degree when they are from eighteen to twenty-one is not "so disproportionate" that "it 'shocks the conscience and offends fundamental notions of human dignity,'" id., quoting Cepulonis, 384 Mass. at 497, the sentence does not violate art. 26's proscription against cruel or unusual punishment. It therefore must be upheld. Background. On September 25, 2011, fourteen year old Kimoni Elliott was visiting his schoolmate and friend, Jaivon Blake, who lived in the area of Geneva Avenue and Everton Street in the Dorchester section of Boston. Elliott lived on Everton Street in Dorchester. That afternoon, Elliott was standing 6 outside a convenience store on Geneva Avenue near Levant Street in Dorchester, an area controlled by the "Flatline" gang. Elliott was looking for somebody old enough to purchase rolling papers for marijuana cigarettes for him. The defendant, eighteen year old Sheldon Mattis, was a member of the Flatline gang. He had been playing football on Levant Street with some other people when he observed Elliott walking toward the convenience store. The defendant approached Elliott and offered to purchase rolling papers for him, and after doing so, the defendant asked Elliott where he was from. When Elliott responded, "Everton," the defendant assumed that Elliott was a member of a rival gang. Elliott and Blake then met in a nearby parking lot and started walking up Geneva Avenue towards Blake's home while the defendant returned quickly towards Levant Street. Minutes later, the defendant met with seventeen year old Nyasani Watt on the corner of Levant Street and Geneva Avenue. He turned his bicycle over to Watt and handed Watt his gun. The defendant then pointed out Elliott and Blake to Watt, patted him on the back, and told him that Watt "needed to go handle that." Watt complied. Watt approached the victims from behind while on the bicycle and fired multiple shots at them. Blake fell to the ground and later died from his injuries. Elliott, despite being shot in the neck and arm, survived. 7 Discussion. 1. Judicial review of punishment designated by the Legislature. "[T]he power of punishment is vested in the legislative, not in the judicial department. It is the [L]egislature, not the [c]ourt, which is to define a crime and ordain its punishment." Opinions of the Justices, 378 Mass. at 830 n.7, quoting United States v. Wiltberger, 18 U.S. (5 Wheat.) 76, 95 (1820). Entrusted with this authority, "[t]he Legislature has great latitude to determine what conduct should be regarded as criminal and to prescribe penalties to vindicate the legitimate interests of society." Commonwealth v. Jackson, 369 Mass. 904, 909 (1976). The Legislature's judgment in this area is thus "to be accorded due respect," Opinions of the Justices, supra at 830, and it is subject only to the constitutional limitations imposed by the Eighth Amendment and art. 26, see Jackson, supra. Article 26, which affords greater protections than the Eighth Amendment, proscribes cruel or unusual punishment; the "touchstone" of this proscription is proportionality. Commonwealth v. Yat Fung Ng, 491 Mass. 247, 271 (2021). This "flows from the basic 'precept of justice that punishment for crime should be graduated and proportioned' to both the offender and the offense." Diatchenko I, 466 Mass. at 669, quoting Miller, 567 U.S. at 469. Our role as the judiciary is therefore to determine whether the punishment designated by the 8 Legislature is "so disproportionate to the offense as to constitute cruel [or] unusual punishment."1 Cepulonis, 384 Mass. at 496. "To reach the level of cruel [or] unusual, the punishment must be so disproportionate to the crime that it 'shocks the conscience and offends fundamental notions of human dignity.'" Diatchenko I, 466 Mass. at 669, quoting Cepulonis, 384 Mass. at 497. In conducting this analysis, we consider "contemporary standards of decency which mark the progress of society." Diatchenko I, supra, quoting Good v. Commissioner of Correction, 417 Mass. 329, 335 (1994). "But in judging legislative determinations of crimes and punishments, we exercise our powers of review with great caution." Opinions of the Justices, 378 Mass. at 830. See Jackson, 369 Mass. at 909 ("It is thus with restraint that we exercise our power of review to determine whether the punishment before us exceeds the constitutional limitations imposed by the Eighth Amendment and by art. 26"). "Therefore, in assessing a punishment selected by a democratically elected [L]egislature against the constitutional measure, we presume its validity." Gregg, 428 U.S. at 175. See Jackson, 369 Mass. at 909, quoting Weems v. United States, 217 Article 26 prohibits the infliction of "cruel or unusual 1 punishments," while the Eighth Amendment proscribes "cruel and unusual punishments." 9 U.S. 349, 379 (1910) ("The function of the [L]egislature is primary, its exercises fortified by presumptions of right and legality, and is not to be interfered with lightly, nor by any judicial conception of their wisdom or propriety"). "[W]hile we have an obligation to insure that constitutional bounds are not overreached, we may not act as judges as we might as legislators." Gregg, supra at 174-175. "We may not require the [L]egislature to select the least severe penalty possible so long as the penalty selected is not cruelly inhumane or disproportionate to the crime involved. And a heavy burden rests on those who would attack the judgment of the representatives of the people." Id. at 175. Accordingly, "a heavy burden is on the sentenced defendant to establish that the punishment is disproportionate to the offense for which he was convicted." Commonwealth v. Bianco, 390 Mass. 254, 260-261 (1983), quoting Commonwealth v. O'Neal, 369 Mass. 242, 248 (1975) (Tauro, C.J., concurring). In concluding that the mandatory imposition of life imprisonment without the possibility of parole for individuals from eighteen to twenty-one who have been convicted of murder in the first degree violates art. 26, the court considers contemporary standards of decency and prior [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/cases/9917022. Public record. Not legal advice.