Last week the state of Texas executed Marvin Wilson for the 1992 murder of police informant Jerry Williams. This was done despite Marvin having an IQ of 61. Generally the minimum accepted IQ to qualify someone for the death penalty in the US is 70. Texas State Attorneys countered that the IQ argument is based on just one test and that other assessments indicated that Wilson was not mentally impaired.
The death penalty is the ultimate form of punishment and is generally applied in first degree murder cases. It was ruled unconstitutional to put the mentally retarded/disabled to death per the Atkins v Virginia US Supreme Court ruling of 2002. In that ruling the court found such an act to be cruel and unusual punishment and therefore a violation of the 8th Amendment of the US Constitution.
There is now concern that the execution of Marvin Wilson was a violation of the US Constitution as the state of Texas rejects the Supreme Courts ruling.