When mitigation evidence makes a difference: effects of psychological mitigating evidence on sentencing decisions in capital trials

Little empirical research has addressed the effects of psychological or psychosocial evidence on sentencing decisions. The present study found that death-qualified mock jurors were more likely to sentence a defendant to death without mitigating evidence than in a case with mitigating evidence present. Mock jurors were less likely to assign a death sentence in cases that contained one of the following types of mitigating evidence: The defendant was (i) diagnosed with schizophrenia, not medicated, and suffered from severe delusions and hallucinations, (ii) drug addicted and high at the time of the murder, (iii) diagnosed as borderline mentally retarded during childhood, or (iv) severely physically and verbally abused by his parents during childhood.