Encyclopedia of Psychology and Law

executing the mentally retarded was in the 20% to

30% range. More recently, surveys published in 2003

and 2004 found that the rates of support for execution

of the mentally retarded were 12.5% and 29%, respec-

tively. In general, these polls confirm the Court’s find-

ing that such executions violate the community’s

“evolving standards.”

The Role of Mental

Health Professionals

The Atkins court determined that the mentally

retarded suffer from cognitive, behavioral, and voli-

tional impairments that affect their impulse control.

As a result, the death penalty is less likely to be a

deterrent. Furthermore, mentally retarded individuals

are less culpable and thus do not deserve harsh treat-

ment. The Court relied on clinical definitions of men-

tal retardation when identifying three criteria that

determine the existence of mental retardation: subav-

erage IQ, poor adaptive skills, and onset of symptoms

before the age of 18.

The legal system requires mental health profes-

sionals to conduct evaluations to determine a defen-

dant’s level of impairment and mental retardation.

This is not an easy task, as mental retardation is dif-

ficult to identify. Mental health professionals gener-

ally measure IQ, processing ability, decision-making

ability, impulse control, and adaptive functioning.

Critics question whether such tests should be used to

make life-or-death decisions because of their inherent

limitations. For instance, a defendant’s score on an

IQ test is considered a major factor in determining

whether he is mentally retarded. However, “intelli-

gence” is a subjective, multifaceted construct without

a standard test. Instead, an examiner constructs a

unique test for each defendant. Thus, two examiners

would likely create two different tests that could pro-

duce two different scores. IQ tests have been criti-

cized for many reasons, including their lack of

test-retest reliability. Because mental retardation is

such an elusive construct, some trials become battles

of the experts to determine whether or not a person is

mentally retarded.

To complicate things further, there is no uniform

legal definition for mental retardation. Each state can

determine its own standard, which can be a subjective

endeavor. For example, states differ on the IQ score that

indicates mental retardation. Some critics note that,

because of varying standards, a defendant who fits the

criteria for mental retardation in one state would not do

so in another state.

In sum, the Supreme Court has found that the pub-

lic’s standards of decency forbid the execution of

mentally retarded prisoners, an assertion supported by

a great deal of research. Despite the Supreme Court

ruling, the assessment of the mentally retarded comes

with controversy.

Monica K. Miller, Alayna Jehle,

and H. Lyssette Chavez

See alsoDeath Penalty; Juveniles and the Death Penalty;

Mental Illness and the Death Penalty; Racial Bias and the

Death Penalty; Religion and the Death Penalty

Further Readings

Atkins v. Virginia,122 S.Ct. 2242 (2002).

Boots, D. P., Cochran, J. K., & Heide, K. M. (2003). Capital

punishment preferences for special offender populations.

Journal of Criminal Justice, 31,553–565.

Boots, D. P., Heide, K. M., & Cochran, J. K. (2004). Death

penalty support for special offender populations of legally

convicted murderers: Juvenile, the mentally retarded and

the mentally incompetent. Behavioral Sciences and the

Law, 22,223–238.

Caplan, P. J. (2004). Bias and subjectivity in diagnosing

mental retardation in death penalty cases. In P. J. Caplan

& L. Cosgrove (Eds.),Bias in psychiatric diagnosis

(pp. 55–59). Lanham, MD: Jason Aronson.

Penry v. Lynaugh,109 S.Ct. 2934 (1989).

Trop v. Dulles,356 U.S. 86 (1958).

MILDTRAUMATIC BRAIN

INJURY, ASSESSMENT OF

An uncomplicated mild traumatic brain injury (mTBI)

is traumatic brain injury in which there is a brief loss

of consciousness, brief posttraumatic amnesia, or an

alteration of mental status (e.g., feeling dazed) with-

out evidence of neurological damage. Physical, cogni-

tive, and psychological symptoms are common in the

days and weeks immediately following the injury, but

these resolve naturally within a few months in the vast

majority of patients. A relatively small number of

patients show continued symptoms, which can be

due to a range of other issues besides the mTBI.

Psychological evaluation of these patients should

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