Defining Intellectual Disability: The Case of Hall Versus Florida

March 3, 2014

In March, the Supreme Court will need to set a national standard for the definition of intellectual disability. In doing so they will inevitably have to address a number of complications that arise when clinical constructs, such as intellectual disability, are used in the courtroom.

A decade ago, in Atkins v Virginia,536 U.S. 304 (2002), the US Supreme Court found the execution of intellectually disabled offenders to be unconstitutional, violating the Eighth Amendment prohibition on cruel and unusual punishment.1 The Court noted a significant change in public attitude toward the execution of the intellectually disabled, evident in the increasing number of states that prohibited the executions, and which they attributed to evolving standards of decency.

Although Atkins v Virginia established a Federal prohibition against using the death penalty for intellectually disabled offenders and cited the American Psychiatric Association (APA) and American Association of Mental Retardation definitions, it left the individual States the task of defining intellectual disability themselves, as well as setting the legal standard to which the definition would have to be held to qualify for exemption. This has resulted in variation from state to state in the way that Atkins has been applied.

[[{"type":"media","view_mode":"media_crop","fid":"23254","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_4474023283772","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"1799","media_crop_rotate":"0","media_crop_scale_h":"175","media_crop_scale_w":"150","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right;","title":" ","typeof":"foaf:Image"}}]]In March 2014, the US Supreme Court will hear Hall v Florida 133 S.Ct. 2025 (2013) on the issue of how Florida has implemented the Atkins mandate. Freddie Lee Hall, who was found guilty of rape and murder, had been found intellectually disabled. However, on the basis of a more recent IQ test on which he scored one point above the cutoff for intellectual disability, Florida decided that he wasn’t, and sentenced him to death. An amicus brief filed by a group of organizations in December 2013, including the American Psychological Association, the APA, and the American Academy of Psychiatry and the Law, criticized Florida’s use of IQ testing alone, claiming it was in violation of Atkins, describing it as a “failure to follow the correct diagnostic approach.”2 They continued:

"In assessing whether an individual meets the clinical definition of intellectual disability, there is a unanimous consensus among the mental health professions that accurate diagnosis requires clinical judgment based on a comprehensive assessment of all three criteria: general intellectual functioning, adaptive functioning, and age of onset."2

The flaw in Atkins was to fail to set a standard for “the correct diagnostic approach.” Florida was able to violate the spirit of Atkins because it was not constrained by any clear definition of intellectual disability.

To prevent future situations like Hall, The Supreme Court will need to set a national standard for the definition of intellectual disability. In doing so they will inevitably have to address a number of complications that arise when clinical constructs, such as intellectual disability, are used in the courtroom.

As discussed above, intellectual disability is generally defined by three criteria in the clinical context. Each of these factors can be quantified and so can be used to define boundaries, or cutoffs. In the legal context, cutoffs are routinely used for IQ score and often for developmental age, but less commonly for adaptive function. In response to Atkins, a number of states specified cutoff scores in their definitions of intellectual disability.

While it is understood both in science and in clinical practice that cutoffs of this type are bound to be made at points that do not reflect actual thresholds, legal decision-making depends on categorical differences. For example, it is impossible to pinpoint, exactly, when the developmental period ends, and furthermore, it probably varies from individual to individual. This is not to deny that there is a difference between what lies on one side of the cutoff and the other. It does however show that the cutoff is almost meaningless in an individual cae. The problem, more generally, is in applying statistical concepts that describe continua and groups to individual cases.

One solution would be to liberalize the cutoffs beyond the possible margin of error.  Some states have already taken this approach to implementing Atkins. For example, Arizona and Ohio have IQ cutoffs of 75 (70 is more common); and Indiana, Montana, Oklahoma, Utah specify developmental age greater than 22 years (18 years is more common). This approach would increase the number of people ineligible for the death penalty.

An alternative approach would be to require the engagement of mental health professionals to make the diagnosis. This approach is advocated in the December 2013 amicus brief mentioned above, and has already been implemented by a number of states, explicitly in some cases, and in others by the absence of concrete statutory guidance (including cutoffs). This approach would also be more consistent with the direction that was taken in the revamp of the DSM, which stresses the importance of a holistic conceptualization of intellectual disability, one aspect of which is deemphasizing cutoffs.

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This article was originally posted online on February 18, 2014.


Dr Westphal is Assistant Professor in the Division of Law and Psychiatry at Yale University, New Haven, Connecticut. Ms Mukherjee is an undergraduate student at Emory University in Atlanta, Georgia.


1. Accessed February 18, 2014.
2. Amicus brief [pdf].  Accessed February 18, 2014.