An Examination of the Effects of Mental Disorders as Mitigating Factors on Capital Sentencing Outcomes

Mentally ill and emotionally disturbed offenders comprise a significant component of those whose criminal conduct has swept them into the criminal justice system, including a subset who are tried and convicted of capital murder. The present study employs the population of capital cases advanced to penalty phase in the state of North Carolina (1990–2009) to examine whether presentation to the jury of the statutory mitigators of extreme mental and emotional disturbance and capacity impaired, and specific mental illness diagnoses, often referred to as mental disorders, at the sentencing phase mitigate against a sentence of death. Mental disorders included mood disorders, psychotic disorders, anxiety disorders, brain disorders, multiple mental illness diagnoses, learning disabilities, and personality disorders. Results from these 835 cases indicate that with the exception of one, the diagnosis of a learning disability, the capital jury's acceptance of various mental health conditions does not effectively mitigate against a capital sentence. In addition, jury rejection of a diagnosis of mental illness or the two mental health statutory mitigators, capacity impaired and extreme emotional disturbance, as a mitigating factor has a counter-mitigating effect in that it significantly increases the odds of a death penalty recommendation by about 85–200%.