The Supreme Court says states must look beyond an intelligence test score in borderline cases of mental disability to determine whether a death row inmate is eligible to be executed.

The Supreme Court today made it more difficult for states to impose the death penalty on prisoners who claim they have a mental disability. 

The court ruled that Florida must factor in a margin of error to IQ tests administered to Freddie Hall, 68, who killed a pregnant woman and sheriff's deputy in 1978. 

Florida had argued that any test score over 70 made prisoners eligible for the death penalty, even though medical guidelines permit scores to reach 75. 

The high court ruling of 5-4 by Justice Anthony Kennedy and the court's four liberal justices will affect a handful of states that have similar policies to Florida. 

This is the first time the Supreme Court has fine-tuned a 2002 decision barring the execution of mentally disabled people. 

Read the Supreme Court's opinion, here.