Defining intellectual disability and establishing a standard of proof: suggestions for a national model standard.

Author:Cheung, Natalie

CONTENTS INTRODUCTION I. DEFINING INTELLECTUAL DISABILITY A. Professional Organizations' Diverging Definitions B. Current APA Definition and the Revised DSM-V II. SUBSTANTIVE DIFFERENCES BETWEEN VARIOUS STATE STATUTES AND CASE LAW A. Varying IQ Cutoff Scores and Presumptions of Intellectual Disability 1. Different IQ Cutoff Scores 2. IQ Scores as Rebuttable Presumptions B. Differences in Defining Limitations in Adaptive Behavior C. Varying Age-of-Onset Requirements III. PROCEDURAL DIFFERENCES AND VARIATIONS IN BURDEN OF PROOF A. A Judge or Jury Decision? B. Varying Qualifications for Testifying Experts C. Divergent Standards for Defendants' Burden of Proof IV. THE NEED FOR A NEW INTELLECTUAL DISABILITY STANDARD A. Why a Change in the Law Is Needed B. Substantive Differences 1. The Effect of Varying IQ Cutoff Scores 2. Subjective Determination of Adaptive Behavior 3. The Age-of-Onset Requirement Is Not Ideal C. Procedural Differences: Determinations Made by Jury versus Judge V. RECOMMENDED NATIONAL STANDARD: A MODEL FOR ESTABLISHING INTELLECTUAL DISABILITY A. Definition of Intellectual Disability and Elimination of Age Eighteen Onset Requirement B. Rejecting a Fixed IQ Cutoff Score C. Guidelines for Adaptive Behavior Evidence D. Judge and Jury Decision E. Standard for Testifying Experts F. Standard for Burden of Proof CONCLUSION INTRODUCTION

In 2002, an intellectually disabled man, Daryl Renard Atkins, sat on death row after a capital murder conviction. (1) Mr. Atkins was diagnosed as "mildly mentally retarded" after a forensic psychologist reviewed his school and court records and interviewed people who knew him. (2) As further proof of intellectual disability, Mr. Atkins scored fifty-nine on an IQ test. (3) After reviewing Mr. Atkins' records, the US Supreme Court made a precedent-changing decision (4) in which it held that the execution of intellectually disabled persons (5) is unconstitutional as a violation of the Eighth Amendment's (6) restriction on "cruel and unusual punishments." (7)

The Atkins Court held that the nation's "evolving standards of decency" precluded states from taking the life of an intellectually disabled offender. (8) The Supreme Court cited, in part, two reasons for its decision: (1) retribution, the justification typically accepted as a basis for the death penalty, may not apply to intellectually disabled offenders; (9) and (2) intellectually disabled defendants are "less able to give meaningful assistance to their counsel and are typically poor witnesses, and their demeanor may create an unwarranted impression of lack of remorse for their crimes." (10) Because intellectually disabled defendants are not capable of controlling their impulses or engaging in logical reasoning, they are unable to understand the reason for their punishment. (11) Thus, executing these individuals "is nothing more than the purposeless and needless imposition of pain and suffering, and hence an unconstitutional punishment." (12)

The Court left to the states the task of developing appropriate ways to enforce this constitutional restriction. (13) However, the Court provided guidelines to the states by quoting intellectual disability definitions promulgated by the American Psychiatric Association (APA) in its Diagnostic and Statistical Manual IV (DSM-IV) and the American Association of Mental Retardation (now known as the American Association on Intellectual and Developmental Disabilities (AAIDD)). (14) Though the definitions of intellectual disability endorsed by the APA and the AAIDD are similar, they are not identical. This difference created confusion among the states concerning which definition to follow. Ultimately, some states applied the APA's definition while others applied the definition from the AAIDD. Additionally, the two definitions only address what constitutes intellectual disability and not the legal requirements for proving the disorder. Thus, the Court left states no guidance on the procedural aspects of adjudicating these types of cases. Consequently, the states have varying definitions of intellectual disability and diverse procedures for proving a defendant's mental capacity. This variation creates disparity amongst the states whereby a defendant executed in one state could have been considered intellectually disabled and thus ineligible for execution in another.

It is unknown whether the Court failed to foresee the problems that would arise in applying Atkins or purposefully neglected to address them. After ten years of nationwide confusion regarding application of the Atkins decision, states have created multiple standards for what evidence is necessary to prove intellectual disability, the standard of proof necessary, what type of qualifications are needed to testify as an expert, and whether the determination of a defendant's mental capacity should be made by a judge or jury. (15) The Atkins Court set out to protect all individuals with intellectual disabilities, (16) but some states have enacted statutes or upheld case law that is inadequate to protect intellectually disabled persons. Thus, the time has come for states to adopt a new test for the purpose of proving intellectual disability and protecting all intellectually disabled individuals.

In this Note, I suggest a new model definition and standard of proof that all states should apply for determining intellectual disability. In doing so, I analyze the varying standards currently in force in several states and identify those that fail to adequately protect the intellectually disabled and those that best promote the underlying goal of Atkins. In demonstrating why a new standard for defining and establishing a defendant's intellectual disability is needed, I use cases from various jurisdictions to show how a defendant's outcome would be different in one state compared to another with different standards. Part I discusses the varying definitions of intellectual disability and the symptoms and characteristics associated with the disorder. It also considers the proposed changes the APA and the AAIDD are making to their definitions of intellectual disability and the impact of these changes. Part II describes several states' varying standards for defining and establishing intellectual disability. Part II also analyzes statutes and cases that apply various Intelligence Quotient (IQ) cutoff scores, differing standards for demonstrating adaptive functioning, and fluctuations regarding the age-of-onset requirement, including evidentiary differences. Part III examines the procedural and burden of proof variations between the states. This includes differences in whether a judge or a jury makes the determination of a defendant's mental capacity, the varying qualifications for testifying experts, and the divergent standards for the burden of proof. Part IV explains the urgent need for change in several states' current intellectual disability laws. Part V proposes a new optimal standard for defining intellectual disability, including evidentiary and procedural standards that all states should adopt.


    1. Professional Organizations' Diverging Definitions

      Since 1876, the AAIDD has been one of the leading organizations dedicated to helping individuals with mental disabilities in the United States. (17) Its mission is to "promote progressive policies, sound research, effective practices, and universal human rights for people with intellectual and developmental disabilities." (18) The AAIDD publishes two journals, the American Journal on Intellectual and Developmental Disabilities and Intellectual and Development Disabilities. (19) For these reasons, the AAIDD was one of the primary resources for the Supreme Court in Atkins and remains a principal guide for many state courts and legislatures attempting to understand and define intellectual disability today. (20)

      Another association recognized for its contributions to mental health is the APA. Established in 1844, (21) the APA is the "world's largest psychiatric organization ... [representing] more than 36,000 psychiatric physicians from the United States and around the world." (22) Part of the organization's mission is to "work together to ensure humane care and effective treatment for all persons with mental disorders, including intellectual developmental disorders and substance use disorders." (23) The APA publishes one of the most widely utilized manuals on mental disorders, known as the Diagnostic and Statistical Manual (DSM). (24) The DSM describes and classifies mental disorders and is used by "health and mental health professionals, including psychiatrists and other physicians, psychologists, social workers, nurses, occupational and rehabilitation therapists, and counselors." (25)

      The Atkins Court quoted the definition of intellectual disability the AAIDD set forth in 1992. (26) Ten years later, the AAIDD revised that definition, (27) though there were no significant changes to the substantive characteristics of the disorder. (28) The AAIDD further updated its definition of intellectual disability in 2010 by changing the terminology from "mental retardation" to "intellectual disability." (29) The 2010 definition is the most current and is substantively the same as the 2002 definition. (30) Today, the AAIDD states that "[i]ntellectual disability is ... characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills ... [and this] disability originates before the age of 18." (31) The AAIDD explained that "the term intellectual disability covers the same population of individuals who were diagnosed previously with mental retardation in number, kind, level, type and duration." (32) The change in terminology from mental retardation to intellectual disability was motivated by a desire to be less offensive to persons with disabilities. (33)

      The AAIDD's...

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