The Supreme Court today ruled that states cannot rely on IQ tests alone to gauge whether death row inmates are "intellectually disabled" and thus eligible to avoid execution. Today's decision impacts borderline cases where a defendant’s IQ score falls within the test’s margin of error, making it harder to impose the death penalty in those situations. It's the first time the Supreme Court has expanded on a landmark 2002 decision that excluded mentally disabled people from capital punishment. It may also ultimately save the life of Freddie Lee Hall, who has spent over 35 years on death row after being convicted of a 1978 murder.

Until now, Florida and other states have adhered to policies that establish a strict cutoff, based around IQ scores, in determining eligibility for the death penalty. In Florida's instance, the state previously said any inmate with a score higher than 70 could be put to death. But during arguments, Hall's lawyers insisted there's plenty of evidence showing him to be mentally disabled — despite IQ scores that put him above the crucial 70 mark. Joined by mental health organizations, they also argued that Hall's tests didn't factor in the inherent five-point margin of error built into IQ assessments. That extra wiggle room would give inmates (including Hall) the chance to continue arguing their case of mental instability.

IQ scores should only be one factor in determining who can be put to death

"The Florida statute, as interpreted by its courts, misuses IQ score on its own terms; and this, in turn, bars consideration of evidence that must be considered in determining whether a defendant in a capi­tal case has intellectual disability," the court said in its opinion. "Freddie Lee Hall may or may not be intellectually dis­abled, but the law requires that he have the opportunity to present evidence of his intellectual disability, including deficits in adaptive functioning over his lifetime."

"The death penalty is the gravest sentence our society may impose. Persons facing that most severe sanction must have a fair opportunity to show that the Constitution prohibits their execution," the court said. Hall was convicted and sentenced to death for the abduction and murder of a 21-year-old pregnant woman. He later killed a sheriff's deputy. The decision comes as capital punishment — specifically lethal injection — is once again under intense scrutiny in the United States. Trouble locating the necessary drugs to carry out lethal injections has led to more than one botched execution and an outcry from death penalty critics.