Adolescent brain science after Graham v. Florida.

• Author: Maroney, Terry A.

INTRODUCTION

In Graham v. Florida, (1) the Supreme Court held that the Eighth Amendment prohibits a sentence of life without possibility of parole for a nonhomicide crime committed when the offender was under the age of eighteen. (2) Justice Kennedy's majority opinion (3) in this closely watched case is remarkable for a number of reasons, chief among them its rejection of the "death is different" mantra (4) that had for so long prevented principles from death penalty jurisprudence from informing constitutional bounds on term-of-years sentencing. (5) Having broken down that wall, the Graham Court easily applied to juvenile life without parole the developmental conclusions that had partially underlain its earlier abolition of the juvenile death penalty. (6)

Developmental neuroscience--that is, the study of life-course changes in the brain's structure and function (7)--contributed to this aspect of Graham. Justice Kennedy, citing to amicus briefs from the American Psychological Association and American Medical Association, wrote that: "[D]evelopments in psychology and brain science continue to show fundamental differences between juvenile and adult minds. For example, parts of the brain involved in behavior control continue to mature through late adolescence." (8)

In an earlier article, The False Promise of Adolescent Brain Science in Juvenile Justice, this author noted the pendency of Graham and its companion case, Sullivan v. Florida. (9) Because both Terrance Graham and Joe Sullivan offered scientific arguments closely paralleling those made by the defendant in Roper v. Simmons, (10) and because largely the same lineup of amici had done the same, I predicted that "[t]he Court's treatment of developmental neuroscience may provide valuable insight, largely absent in Roper, to its attitude toward its relevance." (11) Did it?

It did. Justice Kennedy's opinion in Graham clarified what his opinion in Roper had left ambiguous: the Court (or at least a majority of its members at that time) believed neuroscience relevant to general propositions as to the normal developmental course of adolescence. To the extent that such propositions drove conclusions as to juveniles' special legal status, neuroscience partially supported those conclusions.

This Essay analyzes the influence of neuroscience in Graham and offers some predictions as to the decision's future impact. As this issue was explicitly set to one side in False Promise, the Essay provides an opportunity to both supplement that article and reflect on its conclusions.

Part I distills its essential arguments and reports on subsequent developments. Part II more closely dissects the neuroscientific arguments made by the defendants and amici in Graham and Sullivan, as well as the Court's treatment of those arguments. Part III reflects on the possible impact of the decision. I predict that its most dramatic effects will have little to do with developmental neuroscience. As to that science, I argue that the Graham Court gave it the maximum weight it presently can bear. The decision therefore provides welcome support for legal policy-makers--whether in courts or legislatures--who seek to draw modestly on such science in reinforcing commitments to the special legal status of youth. But the predictable post-Graham temptation to place even greater weight on developmental neuroscience should--for the many reasons articulated in False Promise, which remain unaltered--be resisted.

1. ADOLESCENT BRAIN SCIENCE IN JUVENILE JUSTICE

   In False Promise I sought to measure the legal impact of developmental neuroscience by identifying and analyzing cases in which arguments relying on such science--sometimes marginally, often centrally--had been made before the courts. I demonstrated that most such arguments fail to persuade and sought to explain why. Just as important, I undertook to explain why developmental neuroscience claims should have only a modest legal impact, and that only within limited parameters. My essential claims were as follows.

   Over the last decade, developmental neuroscience has generated a scientific consensus that, when considered in the aggregate, teen brains are structurally and functionally different from those of both children and adults. As those differences are nonnegligible and as they appear to map onto teens' social and decisional immaturity, juvenile advocates and defenders quickly began to incorporate neuroscientific claims into ones grounded in developmental psychology. (12) Nowhere was this truer than in Roper. (13) Defendant's counsel and amici highlighted neuroscience in both briefing and argument. (14) The Roper Court relied in part on developmental principles to hold that the juvenile death penalty offends the Eighth Amendment, and in so doing nodded to the proffered "scientific" studies. (15) Though the Court nowhere singled out brain science, Roper was widely interpreted to reflect its endorsement of such science. (16)

   Building on a theme begun before Roper, prominent theorists then held out developmental neuroscience as evidence strongly supporting a "diminished culpability" model that, they argued, compelled a host of policy and legal conclusions going well beyond the death penalty. (17) Juveniles and young adults followed suit, raising brain science claims in a wide variety of cases. (18) Close review of those cases revealed three core phenomena.

   First, many courts regarded brain science claims as falling outside the narrow parameters dictated by applicable doctrine. (19) In the context of juvenile life without parole (JLWOP), most courts believed the "death is different" rationale and Roper's apparent approval of JLWOP together to foreclose the relevance of Roper-style developmental arguments, including their neuroscientific aspect. (20) Courts instead tended to rely on gross disproportionality tests, to which the relevance of developmental factors was unclear, to uphold virtually all term-of-years sentences. (21) A similar heavy deference to state legislative schemes underlay courts' tendency to reject brain-based challenges to transfers to adult court, liability for felony murder, construction of mens rea terms, such as specific intent and reasonableness, and waiver of rights. (22)

   Second, courts frequently rejected brain science claims where they appeared either to contradict or to duplicate record facts. (23) Exemplifying the former were cases contesting the mens rea element of specific intent. Many such cases involved juveniles whose actions suggested relatively high levels of planning and forethought, taken to obviate the relevance of findings that juveniles generally lack adult levels of such capacity. (24) In the latter category fell cases in which courts believed brain science to add little to evidence of immaturity that already was before factfinders--or that would add little to adults' "common sense" understanding of the attributes of youth. (25)

   Third, the minority of courts that did credit neuroscience appeared to do so only marginally. (26) That is, such science likely was invoked to buttress a conclusion to which they already were inclined and that was adequately supported by ample other grounds.

   Taken together, the analysis demonstrated that the persuasive power of adolescent brain science in the courts was falling far short of expectations. Much of this shortfall was attributable to contemporary doctrine, which tends to be hostile toward most juvenile claims. (27) The case analysis sought not to critique doctrine but to demonstrate the fate (and likely fate) of claims made in that difficult environment. (28) I also sought to explain the limited impact of adolescent brain science by reference to confirmation bias, as legal decisionmakers filter such evidence through prior beliefs and values. (29)

   Beyond the external limitations of extant doctrine and the internal limitations of human bias, I also argued that aspects of the science itself necessarily limit its relevance. (30) Because the data support conclusions only at the aggregate level, they shed little light on the developmental status of any given young person, except insofar as she is a member of the group. While links between structural attributes, brain-level functional data, and externalized behaviors are strengthening, they remain largely speculative. Juveniles' relative deficiencies do not invariably mean they fall below legal thresholds. As the described developmental trends extend into early adulthood, they do not provide a compelling basis for extending benefits to persons under eighteen but not to "emerging adults." (31) Taking brain development as the primary metric by which to dole out legal rights and protections, moreover, could be understood to threaten juvenile autonomy and to invite discriminatory distinctions between groups according to their relative propensities toward early or late development. (32)

   Thus, courts are largely justified in taking adolescent brain science as--at most--a body of evidence lending marginal support to traditional (if embattled) assumptions underlying youths' special legal status. (33) Transformation in juvenile law and policy will flow not from that science but rather from recommitment to creating both societal conditions that support healthy growth and humane legal responses that maximize youthful offenders' future potential. (34)

   Other juvenile justice theorists have in the interim endorsed much of this author's analysis. (35) And since False Promise went to press, setting aside for the moment Sullivan and Graham, the case law has continued to develop largely along the same lines. Mens rea challenges have continued to run aground. A New Mexico teenager convicted of premeditated murder, for instance, was denied postconviction relief despite an argument that her brain was "controlled primarily by the impulsive and hyperactive amygdal[a]," such that she was "likely physiologically and biologically incapable of...