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By Chad Berryman, Volume 108 Staff Member

In July 2022, the Michigan Supreme Court decided People v. Parks, in which it held that mandatory life without parole sentences for eighteen-year-olds convicted of first-degree murder violate the Michigan Constitution’s prohibition of cruel or unusual punishment.[1] This ruling went beyond prior U.S. Supreme Court decisions such as Miller v. Alabama, which held that mandatory life without parole sentences for juvenile offenders violate the U.S. Constitution.[2] However, the Parks court did not explain why such punishments should be permissible for nineteen-year-olds.[3] This Post argues that the court’s reasoning suggests it also would reject mandatory life without parole sentences for nineteen- or twenty-year-olds if presented with the proper case.[4]

I. Context

Like the U.S. Constitution, the Michigan Constitution prohibits inflicting certain types of punishments on criminals.[5] However, there is an important difference between the two constitutions: the former bans cruel and unusual punishments, while the latter bans cruel or unusual punishments.[6] Michigan courts have consequently held that their state constitution prohibits a broader range of punishments than does the U.S. Constitution.[7]

This constitutional difference is crucial because, as the Parks court acknowledged, turning eighteen does not involve a mystical ascension to maturity.[8] The court assessed the relevant science and concluded that “[o]verall, late-adolescent brains are far more similar to juvenile brains . . . than to the brains of fully matured adults.”[9] The court therefore found prior Supreme Court Eighth Amendment cases “persuasive to the extent they held that juveniles are constitutionally different from adults for purposes of imposing a life-without-parole sentence.”[10] Nevertheless, the court decided that sentencing judges must be able to consider eighteen-year-old defendants’ youth during sentencing, just as they would for seventeen-year-olds.[11]

II. The Twist

By itself, this development is significant yet eminently logical.  Much contemporary debate concerning cruel and unusual punishments centers on the degree to which we should interpret such prohibitions according to “evolving standards of decency.”[12] In doing so, courts often consider the role of science in assessing a defendant’s culpability.[13] This is particularly true for juvenile defendants, with respect to whom the U.S. Supreme Court has declared that their decisions rely “not only on common sense—on what ‘any parent knows’—but on science and social science as well.”[14] Thus, the Michigan Supreme Court’s willingness to affirm the lack of meaningful difference between a seventeen-year-old defendant and an eighteen-year-old defendant is not, on its own, especially shocking.

However, the attorneys in Parks suggested a much stronger tonic.  On appeal, Mr. Parks’ attorneys contended: “The United States Supreme Court’s decisions in Miller v. Alabama and Montgomery v. Louisiana should be applied to people who are eighteen to twenty-five years old at the time they commit a crime and who would otherwise be subject to mandatory life without the possibility of parole.”[15] Similarly, the justices pushed Parks’ attorneys during oral arguments to respond to the obvious line-drawing problem that arises if one includes eighteen-year-olds: why stop at eighteen?[16] The attorneys’ response was identical to the argument in their brief: based on the available science,[17] the line should be drawn at twenty-five years old.[18]

At first blush, this may seem surprising; seventeen to twenty-five is a much bigger jump than seventeen to eighteen. Consequently, Mr. Parks’ attorneys emphasized on appeal the various ways in which our laws provide special protections to young adults.[19] The court explicitly cited several of these examples as supporting its decision; for example, individuals under twenty-one are unable to purchase alcohol or open a credit card without a cosigner.[20] The court’s receptiveness to such analogues implies that the court eventually might have difficulty explaining why, say, a nineteen-year-old defendant should not also receive the same protections as an eighteen-year-old.

III. Around the Bend

A close look at the filings in Parks bolsters this suspicion.  The amicus brief filed by a group of scientists argued that developmental neuroscience supports extending the prohibition to embrace the entire period of late adolescence: ages eighteen, nineteen, and twenty.[21] Indeed, the Parks court used the same terminology in stating that “[b]ecause of the dynamic neurological changes that late adolescents undergo as their brains develop over time and essentially rewire themselves, automatic condemnation to die in prison at 18 is beyond severity—it is cruelty.”[22] Therefore, had Mr. Parks been nineteen or twenty rather than eighteen when he committed his offense, the science most likely would have led the court to the same outcome.

Perhaps such a case will be brought in the future. For now, we are left with an uneasy equilibrium, an attempt to reconcile long-standing norms with novel scientific research.[23] However, this tension is ultimately good.[24]  As one judge so rightly stated:

No matter how long we have done it, we can never forget what an awesome responsibility it is to decide whether and for how long to deprive someone of their liberty . . . . One aspect of that responsibility is to continually reexamine the various components of sentencing and recognize that sentencing, more than any other judicial function, is dynamic and needs constant attention.[25]


[1] People v. Parks, 987 N.W.2d 161, 164 (Mich. 2022) (“[W]e hold that his sentence of mandatory life without parole violates the Michigan Constitution’s ban on ‘cruel or unusual’ punishment.” (citing Mich. Const. art. 1, § 16)).  It is crucial to emphasize that this only applies to mandatory life without parole sentences; sentencing judges still may impose life without parole provided they consider a defendant’s youth as potentially mitigating culpability.

[2] Miller v. Alabama, 567 U.S. 460, 465 (2012) (“We therefore hold that mandatory life without parole for those under the age of 18 at the time of their crimes violates the Eighth Amendment’s prohibition on ‘cruel and unusual punishments.’”).

[3] See Dora W. Klein, Taking Corrigibility Seriously, 28 Berkeley J. Crim. L. 35, 80 (2023) (“The brain development that occurs during adolescence has no clear end point, so at what age should courts say that people are no longer entitled to the special protections afforded to juveniles? The Michigan Supreme Court [in Parks] declined to say how far it believed the protections should extend, ruling only that however far that is, it includes 18-year-olds.”).

[4] Other states have prohibited mandatory life without parole sentences for individuals who were older than eighteen when they committed their crimes. Compare Parks, 987 N.W.2d at 183 (“We hold that mandatorily subjecting 18-year-old defendants convicted of first-degree murder to a sentence of life without parole violates the principle of proportionality derived from the Michigan Constitution . . . and thus constitutes unconstitutionally cruel punishment . . . .” (citations omitted)), with In re Monschke, 482 P.3d 276, 280–81 (Wash. 2021) (“The petitioners have shown that many youthful defendants older than 18 share the same developing brains and impulsive behavioral attributes as those under 18. Thus, we hold that these 19- and 20-year-old petitioners must qualify for some of the same constitutional protections as well.”).  The primary reason for the difference in holdings between Parks and Monschke seems simply to be the age of the defendants.

[5] Compare U.S. Const. amend. VIII (“Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.”), with Mich. Const. art. 1, § 16 (“Excessive bail shall not be required; excessive fines shall not be imposed; cruel or unusual punishment shall not be inflicted; nor shall witnesses be unreasonably detained.”).

[6] See supra note 3; see also William W. Berry III, Cruel State Punishments, 98 N.C. L. Rev. 1201, 1234 (2020) (discussing the important differences and increased breadth that arise from the Michigan Constitution’s disjunctive “cruel or unusual” language).

[7] See Parks, 987 N.W.2d at 169–70 (Mich. 2022) (“[A] bar on punishments that are either cruel or unusual is necessarily broader than a bar on punishments that are both cruel and unusual.” (citations omitted)).

[8] See id. at 175 (“Notably, the prosecution does not even attempt to refute the scientific consensus that, in terms of neurological development, there is no meaningful distinction between those who are 17 years old and those who are 18 years old.”).

[9] Id.

[10] Id. at 173.

[11] Id. at 183 (“The attributes of youth must be considered to ensure that the sentencing of 18-year-old defendants found guilty of first-degree murder passes constitutional muster.”).

[12] See, e.g., Miller v. Alabama, 567 U.S. 460, 510 (2012) (Alito, J., dissenting) (“The Court long ago abandoned the original meaning of the Eighth Amendment, holding instead that the prohibition of ‘cruel and unusual punishment’ embodies the ‘evolving standards of decency that mark the progress of a maturing society.’” (quoting Trop v. Dulles, 356 U.S. 86, 101 (1958))); cf. Roper v. Simmons, 543 U.S. 551, 561 (2005) (“[W]e have established the propriety and affirmed the necessity of referring to ‘the evolving standards of decency that mark the progress of a maturing society’ to determine which punishments are so disproportionate as to be cruel and unusual.” (quoting Trop v. Dulles, 356 U.S. 86, 100–101 (1958))).

[13] See, e.g., Thomas Grisso & Antoinette Kavanaugh, Prospects for Developmental Evidence in Juvenile Sentencing Based on Miller v. Alabama, 22 Psychol. Pub. Pol’y & L. 235, 235 (2016) (“The U.S. Supreme Court established in Roper, Graham, and Miller that adolescent offenders’ immaturity requires special consideration in sentencing. The Court’s three decisions were influenced in part by the convergence of recent normative research on brain development and on behavioral functioning of adolescents.”). But see Terry A. Maroney, The False Promise of Adolescent Brain Science in Juvenile Justice, 85 Notre Dame L. Rev. 89, 117 (2009) (“[T]he courts’ response to adolescent brain science reflects a frequent disconnect between the questions asked by law and those answered by science. Though courts sometimes cite the science approvingly, they do so only to buttress conclusions otherwise fully explained.”).

[14] Miller, 567 U.S. at 471.

[15] Brief of Defendant-Appellant at 9, People v. Parks, 987 N.W.2d 161 (Mich. 2022) (No. 162086), 2021 WL 6426678, at *9.

[16] Michigan Supreme Court, 162086 People of MI v Kemo Parks, YouTube, at 4:03–5:06 (Mar. 3, 2022), (discussing where the line should be drawn based on evolving standards of decency and science of brain development).

[17] Interestingly, the amicus brief filed by a group of scientists and scholars actually argued that the science makes applying mandatory life without parole to eighteen-, nineteen-, and twenty-year-olds unconstitutional. See Brief of Amici Curiae Neuroscientists, Psychologists, and Criminal Justice Scholars in Support of Defendant-Appellant Mr. Parks at 32, People v. Parks, 987 N.W.2d 161 (Mich. 2022) (No. 162086), 2022 WL 541600, at *32 (defining late adolescence as the period from eighteen to twenty years old and concluding that imposing mandatory life without parole sentences on late adolescents “is cruel or unusual, and therefore prohibited by the Michigan Constitution”).

[18] Compare id., with Brief of Defendant-Appellant, supra note 15, at *21 (“From age 18 to 25, individuals become more assertive and decisive, show increases in self-control and ability to resist outside influence, become more reflective, deliberate and planful, and demonstrate decreases in aggressiveness and alienation . . . . These developments correspond to desistance from crime . . . . Research also shows that those 18 to 25 are highly amenable to intervention and rehabilitation.”).

[19] Brief of Defendant-Appellant, supra note 15, at *23–25 (enumerating special legal restrictions on and protections for young adults).

[20] People v. Parks, 987 N.W.2d 161, 175 (Mich. 2022) (specifically citing restrictions on purchasing alcohol, opening a credit without a cosigner, and other restrictions); Brief of Defendant-Appellant, supra note 15, at *23–24.

[21] See Brief of Amici Curiae Neuroscientists, Psychologists, and Criminal Justice Scholars in Support of Defendant-Appellant Mr. Parks, supra note 17, at *3 (“[T]here is no scientific basis for drawing a line at age 18 for when LWOP sentences may be constitutionally applied. To the contrary, the science supports treating these sentences as unconstitutional for late adolescents.”).

[22] Parks, 987 N.W.2d at 168 (emphasis added).

[23] Id. at 182 (“[N]o meaningful neurological bright line exists between age 17 and age 18” (quoting In re Monschke, 482 P.3d 276, 326 (Wash. 2021)).  It is telling that the Parks court relies on Monschke for this proposition because the Washington Supreme Court held in Monschke that mandatory life without parole sentences for nineteen- and twenty-year-olds are unconstitutional under the Washington Constitution.

[24] Certainly, there may be good-faith disagreement over whether this tension is properly housed within the judiciary.  See Parks, 987 N.W.2d at 199 (Clement, J., dissenting) (arguing that the court’s reasoning relies on policy arguments with “no clear limiting principle” and that “[i]t is up to the Legislature to balance the science with society’s penological goals).  However, that this tension appears at all is ultimately good as far as citizens and their rights are concerned.

[25] Timothy J. Corrigan, Who Appointed Me God? Reflections of a Judge on Criminal Sentencing, 100 Judicature 25, 32–33 (2016).