Intellectual disability (ID) is differently yet validly described by different professions. Legal professionals find it most useful to consider ID as a disability rather than a disorder. Because the law regulates the actions of individuals in a society and the actions of society on an individual, the law's concern in dealing with a person with ID is almost always with that person's functional abilities and limitations in society. This concern is reflected in various aspects of criminal and civil law, although the methods of assessing those functional abilities and limitations have changed considerably over time. The law has not always been wise or humane in its treatment of people with ID, but its focus on functional abilities and limitations allows us to assist people with ID to use their abilities and participate in society to their fullest potential.
Intellectual disability (ID) can be envisioned and described in various ways. Different professions have adopted (or at least they start from) different models and vocabulary, and each of the approaches can have value for those of us who work in the field of ID. Although the law has no claim to a superior or more valid view of the subject, like every profession addressing ID, the law's approach brings added value to the overall understanding of the problem. As with all professionals, that value derives from their professional expertise and experience, their insights into the condition, and the essential services that those professionals provide to individuals with ID.
But sometimes it is important for those who craft and implement public policy to evaluate and rely on particular models and vocabulary to make important choices about appropriate services, individual rights, and other legal matters in the lives of people with ID. Recent discussions among mental disability professionals and professional organizations have focused on the comparative values of describing ID as a mental “disorder,” with analogies drawn to mental illnesses such as schizophrenia and depression, or as a mental “disability,” with more similarity to physical impairments like blindness and deafness.
This is not, of course, a rigid either–or choice; there are values and elements of truth in both models. Obviously, an understanding of some forms of ID include medical questions (e.g., chromosomal abnormalities in a subset of individuals with ID), whereas broader issues of societal adaptation and equal treatment are more closely akin to comparable issues involving people with other forms of disability.
Whether the phenomenon of ID is more usefully thought of as primarily a disability or a disorder requires some reflection on the lives of people with ID and the nature of society's responses to them. This article seeks to offer a perspective on the law's approach to these questions.
Unlike some other professions, courts and legislatures focus on ID only when its presence (or absence) may be relevant to some particular legal question, such as property ownership, validity of contracts, guardianship, civil or criminal responsibility for a person's actions, educational opportunities, competence to stand trial or participate in legal proceedings, protection from discrimination, and the provision of services (whether voluntary or involuntary).
In each of these areas, Anglo-American law has traditionally viewed ID as being primarily about the functional limitations of an individual who has it. As a general matter, issues such as etiology are viewed as legally unimportant, or, at least, far less important than functional assessments.
This functional approach has a long history. As early as the 16th century, the influential judge and legal scholar Sir Anthony Fitzherbert, defined idiot for legal purposes as “a person who cannot account or number twenty pence, nor can tell who was his father or mother, nor how old he is, etc., so as it may appear he hath no understanding of reason what shall be for his profit, or what for his loss” (cited in Glueck, 1925, p. 128, and Ellis & Luckasson, 1985, p. 416). This “counting twenty pence” test has been described as “a crude but by no means ridiculous form of intelligence test” (Walker, 1968, p. 36).
The definitions used by medical professionals and others evolved over the intervening centuries, and terminology and classification systems were developed (Ray, 1838, pp. 59–60; Report of the Committee on Classification of the Feeble-Minded, 1910), which often strike modern readers as crude, uninformed, insensitive, and based on gross stereotypes (Trent, 1994). But even in those eras of deeply flawed understanding of the origins and manifestations of intellectual limitations, courts and legislators frequently focused on what they perceived to be the actual relevance of the practical impact of an individual's mental disability on the legal question presented by a particular case (Grasset, 1907).
That focus on functioning continues in today's courts. Although justices in the landmark U.S. Supreme Court Cleburne decision acknowledged that the history of our nation's mistreatment of people with mental retardation was “grotesque” (City of Cleburne v. Cleburne Living Center, 1985, pp. 454, 461; hereafter, “Cleburne”), the majority focused on what they saw as the group's salient attribute: “Those who are mentally retarded have reduced ability to cope with and function in the everyday world” (Cleburne, 1985, p. 442). The justices then, unanimously declared the exclusion of a group home from the community to be unconstitutional because, as Justice White wrote for the majority, “The short of it is that requiring the permit in this case appears to us to rest on an irrational prejudice against the mentally retarded” (Cleburne, 1985, p. 450). In other words, the Supreme Court saw the most relevant characteristic of the group to be functional limitations, but struck down a law that imposed unwarranted legal limitations on individuals with ID when it was based on irrational societal prejudice against those individuals.
Even when it confronted a case that involved an allegation of mental illness—a condition that more clearly fits within the “disorder” model than does ID—the Supreme Court held that the U.S. Constitution barred a state from depriving a person of liberty solely on the basis of a diagnostic label. In O'Connor v. Donaldson (1975), the Supreme Court unanimously held that:
a finding of “mental illness” alone cannot justify a State's locking a person up against his will and keeping him indefinitely in simple custodial confinement. Assuming that that term can be given a reasonably precise content and that the “mentally ill” can be identified with reasonable accuracy, there is still no constitutional basis for confining such persons involuntarily if they are dangerous to no one and can live safely in freedom. (p. 575)
As the Donaldson decision makes clear, there are constitutional limits on the government's ability to take away a person's liberty when its only justification is a psychiatric diagnosis. (Similar issues of institutional confinement and conditions, involving both mental illness and ID, are now most frequently addressed by the courts within the statutory context of the Americans with Disabilities Act of 1990 [ADA; see Olmstead v. L.C., 1999].)
The ADA protects people with mental and physical disabilities from discrimination. The statute defines mental disabilities as “any mental or psychological disorder, such as mental retardation, organic brain syndrome, emotional or mental illness, and specific learning disabilities” (Parry, 1997, p. 9). But, although the statute refers to the term “disorder,” the scope of the law's actual protection extends only to disabilities that substantially limit major life activities (working, learning, self-care, interacting with others, etc.), and whether a particular individual's impairment is “substantial” is the issue on which many ADA cases turn (Parry, 1997).
Similarly, in a wide variety of legal issues, individuals with ID are identified for differential treatment based on the functional consequences of their condition, rather than on the basis of its etiology or medical classification. For example, in the criminal justice system, if the question is raised whether a particular defendant is competent to stand trial, the legal test will be whether, because of his mental condition, “he has sufficient present ability to consult with his lawyer with a reasonable degree of rational understanding—and whether he has a rational as well as factual understanding of the proceedings against him” (Dusky v. United States, 1960, p. 402; American Bar Association, 1989a). If the case is to be resolved by a guilty plea, the ability to enter such a plea will also involve an inquiry into the defendant's functional understanding and ability (American Bar Association, 1989b; Brief for the American Psychiatric Association et al., 1993; Godinez v. Moran, 1993). If a defendant wishes to waive one of his constitutional rights, the validity of that waiver will depend on the court's determination about whether his mental disability prevented him from understanding his rights and knowingly choosing to waive them (Johnson v. Zerbst, 1938).
The same kind of focus on the potential impairment in an individual's functioning guides the civil law as well. Both courts and legislatures emphasize the actual disabling effect of ID, rather than focus on the particulars of diagnosis or etiology. For example, when a guardianship is proposed for a person who is alleged to have a mental disability, the legal inquiry will be about that person's actual ability or inability to manage his or her personal or financial affairs (or those portions of everyday affairs in which the disability makes a “limited purpose guardianship” appropriate; see Drogin and Barrett, 2013; Sales, Powell, & van Duizend, 1982). Similarly, the test for mental competence to be a witness in court is purely functional. “Whether the witness has enough intelligence to make it worthwhile to hear him at all and whether he recognizes a duty to tell the truth. Does he possess enough capacity to perceive, record, recollect, and narrate to probably add valuable knowledge of the facts to the record?” (Broun, 2006, p. 116). Capacity to make a valid will is also focused on practical impairments, including knowing the nature and extent of the individual's property, knowing the people most likely to be recipients of his bounty, and understanding that his property will be distributed after his death according to the will he is signing (McGovern, Kurtz, & English, 2010, p. 316). Incapacity to enter into an enforceable civil contract “exists where a party does not understand the nature and consequences of what is happening at the time of the transaction” (Perillo, 2009, p. 263).
In each of these areas of law, the source of the potential functional impairment does not matter much. The legal test is the same whether the potential obstacle to competence derives from ID, mental illness, mental impairment accompanying advanced age, or some other mental condition.
The law's approach to individuals with ID and their role in society has not been uniform over time, of course, or uniformly wise or humane. In Buck v. Bell (1927; hereafter, “Buck”), the U.S. Supreme Court upheld a eugenics sterilization statute in the case of Carrie Buck, a woman who was alleged to have mental retardation. The Buck case is now infamous for its facile assumption that an individual's mental disability would be genetically transmitted to any children she might bear, and for its chilling (at least to modern ears) rhetoric:
It is better for all the world, if instead of waiting to execute degenerate offspring for crime, or to let them starve for their imbecility, society can prevent those who are manifestly unfit from continuing their kind. … Three generations of imbeciles are enough.” (Buck, 1927, p. 207)
The Supreme Court's decision in Buck is now widely criticized for its factually erroneous premise, its egregious stereotypes, and its dismissive approach to the fundamental rights of people with ID (Bruinius, 2006; Gould, 1984; Kevles, 1985; Lombardo, 2008; Smith and Nelson, 1989). But it may be noteworthy that Buck also represents an instance of both the legislature and the Supreme Court viewing ID through the misleading categorical prism of what was perceived to be a genetically transmitted disorder, rather than a form of disability.
Criminal cases involving a defendant's claim that his or her mental disability should preclude or mitigate the conviction or punishment have a long history in Anglo-American law (Cook, 1921; Ray, 1838; Steadman et al. 1993; Weihofen, 1954). When a criminal defendant offers a plea of not guilty by reason of mental disease or defect (commonly called the “insanity defense,” although it also applies to defendants with ID), the test will be some variant on whether an individual defendant's disabilities, at the time of the crime, prevented him or her from understanding the wrongfulness of his or her conduct or from conforming to the requirements of the law (American Law Institute, 1985; American Bar Association, 1989c; Ellis & Luckasson, 1985). Although establishing the presence of a mental “disease or defect” is a threshold inquiry in such cases, the ultimate resolution will depend on a factual assessment of whether the mental disability produced a functional impairment in the individual's understanding or behavior.
Cases involving the death penalty present particularly sensitive issues when the defendant has a mental disability. One such issue arises when counsel for a condemned inmate seeks to prevent an impending execution because a mental disability renders the defendant incapable of understanding the punishment or incapable of assisting the lawyer in presenting a defense (American Bar Association, 1989d). In 1986, the Supreme Court held that the Constitution prohibits executing condemned inmates whose current mental condition—at the time that execution is imminent—prevent them from understanding the penalty that is about to be imposed (Ford v. Wainwright, 1986). The inquiry in these cases focuses very specifically on the functional consequence of a condemned inmate's mental disability.
More recently, the Supreme Court held that the Constitution's prohibition against “cruel and unusual punishments” (Eighth Amendment to the U.S. Constitution), prevented states from subjecting individuals with ID to the death penalty (Atkins v. Virginia, 2002; hereafter, “Atkins”). In reaching this conclusion, the Supreme Court observed that the enactment of state laws protecting individuals with ID was evidence of a “national consensus” against imposing the death penalty on those individuals (Atkins, 2002, p. 316). The majority also concluded that the effect of their disabilities meant that those individuals had a reduced level of culpability for their actions and, as a result, “death is not a suitable punishment” for an individual with ID (Atkins, 2002, p. 321). In addition, the Supreme Court noted that because of the practical limitations imposed by their disability, such defendants faced extraordinary practical difficulties in capital trials, “Mentally retarded defendants in the aggregate face a special risk of wrongful execution” (Atkins, 2002, p. 321).
Atkins cases involve a hybrid vision of ID. The protection afforded to capital defendants who have that disability is categorical, in the sense that no one who has ID may be executed, and the individual cases will turn on whether the individual defendant meets the legal and clinical definition of “mental retardation” (Ellis, 2003). But the Atkins decision, as well as state statutes prohibiting the execution of individuals with ID, focused very specifically on the practical consequences of the disability, both on the individual's criminal behavior and on the potential for a miscarriage of justice.
There is no single, invariably correct way to think about ID. It is important for us all to understand the etiology, epidemiology, psychology, educational theory and practice, sociology, familial interactions, and the developing discoveries of neuroscience, just to name a few. Judges, lawmakers, and attorneys in individual cases have benefited from the insights in each of these areas and will continue to do so.
However, for the law, understanding ID focuses primarily on what challenges and limitations the disability creates for individuals and the ways in which those limitations can be addressed, accommodated, and ameliorated. Some of the legal changes in recent decades have been symbolic, such as changing the statutory terminology from “patient” to “client” (e.g., Minn. Laws, 1989) and abandoning terminology (e.g., Goddard, 1915; Hooton, 1937) that a later generation deemed stigmatizing (Schalock, Luckasson, & Shogren, 2007). But the more significant changes have involved the recognition that individuals with disabilities are entitled to appropriate services, the law's protection, and legal recognition of their citizenship (e.g., ADA, 1990; Developmental Disabilities Assistance and Bill of Rights Act, 1975; Individuals with Disabilities Education Act, 1975). As we seek to sharpen the law's focus on the needs of individuals with mental disabilities, a careful, and sometimes delicate, balance must be struck between protecting those individuals from harm and enhancing their autonomy in living their own lives (Ellis, 1992).
The law's use of the disability model enhances—in a way that might seem paradoxical at first blush—our ability to recognize and help build on the individual's ability to participate in society to the maximum extent possible.
James W. Ellis is Distinguished University Professor and Professor of Law at the University of New Mexico. He has represented a variety of professional and voluntary disability organizations, including AAIDD, working with legislative bodies and before the Supreme Court of the United States. He served as President of AAIDD (then known as the American Association on Mental Retardation) in 1989–90.