[JURIST] The New Jersey Supreme Court [official website] Tuesday held that mental retardation, like insanity, is a condition to be affirmatively proved by the defense in state death penalty cases. In a 5-2 ruling [text, PDF], the court overturned an August 2005 appeals court decision [PDF] that had placed the onus of disproving mental disability on prosecutors [JURIST report]. Convicted death row inmates now carry the burden of proving mental disability before the sentencing phase of their trials. If they succeed they are sentenced to life imprisonment. If they fail, a penalty-phase trial begins where mental retardation is considered as a mitigating factor when weighing the death penalty [JURIST news archive]. New Jersey joins twenty-eight other states that place the mental retardation burden on defendants.

The ruling arose from the case of Porfirio Jimenez, a day laborer who was convicted in 2001 of sexually assaulting and killing a 10 year old boy after luring him to a secluded area. His defense argued that since his IQ was below 70, a fact corroborated by the prosecution, he was mentally retarded and therefore disqualified from the death penalty. Even if a death penalty were handed down in the case, however, New Jersey has had a moratorium on the practice since 1982 and has not executed an inmate since 1963. In 2002, the US Supreme Court ruled in Atkins v. Virginia [text] that executing mentally retarded individuals is unconstitutional, but left it up to the states to determine the definition of mental retardation. The most common standard is the IQ test. AP has more.