The legal definition of disability is up for debate again after the Supreme Court found that Texas used outdated definitions of intellectual disability in a capital case.
The Court’s ruling in Moore v. Texas establishes the precedent that all states must comply with the most current medical standards for defining intellectual disability, according to the American Association on Intellectual and Developmental Disability’s most recent guidelines.
Moore v. Texas represents a step forward in ensuring justice for a population otherwise marginalized in the criminal justice system.
The most recent standards allow a more holistic evaluation of intelligence testing results and behavioral factors in determining intellectual disability.
Yet, even with improved standards and methods of test administration, the diagnosis of intellectual disability is not an objective determination and historically never has been. It is crucial to recognize the subjectivity that has historically characterized — and continues to characterize — the category of intellectual disability in legal contexts.
The origins of intelligence testing in criminal trials trace back to Henry H. Goddard, an early 20th-century psychologist who is sometimes dubbed “the father of intelligence testing.”
Goddard was responsible for controversial research identifying intellectual disability in immigrant populations on Ellis Island and for work at Vineland Training School, a foremost institution for people with intellectual disabilities at the time.
While theories of eugenics were a defining factor in his work, Goddard’s research on intelligence testing also had progressive implications. His 1915 book “The Criminal Imbecile: An Analysis of Three Remarkable Murder Cases” initiated discussions about whether intellectual disability should be taken into account in criminal trials.
As the dated nature of Goddard’s research shows, intelligence testing has been anything but objective. Goddard’s work, however well-intentioned, hinged on the concept that intelligence is a fixed and quantifiable biological characteristic.
In addition to this flawed underlying principle, the interpretation of intelligence testing relies on a statistical formula rooted in relativism. Intellectual disability is determined with relation to the average score, rather than some absolute, objective determinant.
For those on the borderline of the requisite percentile, the decision becomes highly subjective, and a slight variation in scores could produce a different legal outcome.
In such cases, intelligence test results should never be a primary determining factor, especially when the death penalty is at stake.
Of course, the elimination of intelligence testing would also eliminate quantitative measures in the diagnosis of intellectual disability. Legal situations demand objectivity in the name of justice, and quantitative results facilitate easy comparison with established standards.
But intelligence tests only provide the illusion of objectivity, given that intellectual disability itself is not a fixed, objective category. The more recent standards better account for social factors, such as adaptive behavior, but accurately defining disability remains an implausible prospect.
Much like the definition of disability itself, the outcomes of Moore v. Texas are fundamentally relative. The ruling represents improvement within the limiting legal and medical definitions of disability, but it also reinforces the limitations of these standards and the subjectivity inherent in defining intellectual disability.
kmilvert@umail.iu.edu
