Although their grave illnesses do not excuse these defendants’ crimes, we believe that life imprisonment without the possibility of parole would have been a more appropriate punishment. Illnesses such as schizophrenia and bipolar disorder are characterized by impairments that — when untreated — significantly affect one’s ability to distinguish fact from reality, to make rational decisions or to react appropriately to events and other people. Under these conditions, the degree of culpability may not rise to the level of cold, unimpaired calculus that justifies the ultimate penalty.

In addition, people with severe mental illness are more vulnerable to being wrongfully accused and convicted. Research has shown that such people are overrepresented among cases of false confession because the conditions of their illness — such as proneness to confusion and a lack of assertiveness — may render them more vulnerable to interrogation techniques and impair their ability to invoke their constitutional rights.

Studies have also shown that death- penalty jurors often misunderstand mental illness, which is often viewed as an aggravating factor — that is, a reason to sentence someone to death — rather than as a mitigating factor, which is what it should be. The troubling consequence is that some defendants may end up on death row because of their mental illness.