Description of Mental Illness

Mental illness can be described in a variety of ways. The American Heritage Dictionary (4th edit., 2000) describes it as: “Any of various conditions characterized by impairment of an individual’s normal cognitive, emotional, or behavioral functioning, and caused by social, psychological, biochemical, genetic, or other factors, such as infection or head trauma. Also called emotional illness, mental disease, mental disorder.”

The National Alliance on Mental Illness describes mental illness in the following way:

Mental illnesses are medical conditions that disrupt a person’s thinking, feeling, mood, ability to relate to others and daily functioning. Serious mental illnesses include major depression, schizophrenia, bipolar disorder, obsessive compulsive disorder (OCD), panic disorder, post traumatic stress disorder (PTSD) and borderline personality disorder.

Intellectual Disability, formerly referred to as “mental retardation,” is defined differently than mental illness.

For more information, visit DPIC’s page on Intellectual Disability.

Insanity or mental incompetency is a severe form of mental illness and is addressed separately by the legal system. Condemned prisoners who do not understand what an execution is or lack a rational understanding of why the State wants to execute them are exempt from execution. The Supreme Court first held in Ford v. Wainwright (477 U.S. 399 (1986)) that executing the insane is unconstitutional. It later ruled in Panetti v. Quarterman (551 U. S. 930 (2007)) that a prisoner who understood the legal process can nevertheless be incompetent to be executed if his mental illness prevents him from rationally understanding why he is to be executed. The Court further clarified its incompetency standard in Madison v. Alabama (No. 17-7505 (2019)), ruling that a state cannot execute a prisoner whose mental or medical condition prevents him from rationally understanding why he is to be executed, irrespective of what condition caused his impairment.

However, competency may fluctuate over time. If a prisoner’s mental competency has been restored, he or she can then be executed. Prisoners who are intellectually disabled (formerly, “mentally retarded”) are exempt from the death penalty and cannot be executed. Prisoners who are mentally ill, but not incompetent to be executed, have no such exemption.