A landmark court case is set to take place in the American state of Nevada over whether the state’s death penalty should exempt offenders that are “mentally-ill”. The appeal case concerns Siaosi Vanisi (49), a Tongan man who is currently on death row for murder.

Vanisi was found guilty of murder and sentenced to death in 1999 for the slaying of Reno police officer Sergeant George Sullivan with a hatchet in a completely unprovoked attack near the University of Nevada on 13 January 1998. At his murder trial, testimonies by friends and family of Vanisi detailed bizarre behaviors exhibited by Vanisi prior to the murder such as “rambling”, “poor hygiene” and “lacking a sense of reality”. Despite efforts by his lawyers to pursue an insanity plea, Vanisi refused to co-operate and was deemed “competent” by the court.

However, the decision to impose the death penalty on Vanisi is now being challenged by law professors of the American Bar Association. The prominent organization is backing an appeal case against Vanisi's sentence and wants the Supreme Court of Nevada to exempt mentally-ill offenders from the death penalty.

An amicus curiae brief  [2]filed by the American Bar Association early last month stated, “A categorical bar against executing people suffering from severe mental illness is required to ensure that the death penalty in nevada serves a penological purpose and reflects community standards.”

In it's brief, the American Bar Association argued that mentally-ill people were capable of displaying rationality but “may actively undermine defense attorneys because of thoughts or behaviors that are a symptom of the illness.”

"Neither retribution nor deterrence is served by executing those whose perceptions of reality, logical reasoning and ability to exercise rational judgment are significantly impaired at the time of the crime", the American Bar Association added.

“The Eighth Amendment prohibits the execution of insane people because the influence of mental illness makes those people less culpable than an offender who does not suffer from such an illness. While mental illness may cause a person to have trouble comprehending the proceedings or the wrongfulness of his conduct, many people who suffer from severe mental illness display high intellectual functioning and may even display developmental maturity.”