The U.S. Supreme Court heard arguments Monday in a key death penalty case concerning the execution of prisoners with mental disabilities. Freddie Lee Hall, a convicted murderer, who professionals say is mentally disabled, is challenging Florida’s strict use of an IQ test to determine whether he lives or dies. The Supreme Court banned the execution of mentally disabled prisoners in 2002 but allows states to determine who meets that definition. Florida is among the states where prisoners who score a 70 or higher on an IQ test can be executed, despite other evidence of disabilities. Hall has scored above 70, but multiple medical professionals say he is disabled, and an earlier judge ruled he “had been mentally retarded his entire life.” During arguments Monday, a majority of Supreme Court justices appeared skeptical of Florida’s rigid use of the IQ test.