The Supreme Court banned the death penalty for mentally retarded offenders a decade ago, but Georgia apparently has not gotten the message. It is the only state with a statute requiring a defendant to meet the unfairly heavy burden of proving retardation beyond a reasonable doubt. This stringent standard could be readily manipulated by experts, resulting in unconstitutional executions.

In a closely divided 4-to-3 ruling, the State Supreme Court wrongly upheld the statute on the grounds that the United States Supreme Court left it to the states to set procedures for deciding on retardation. This unjust procedural requirement effectively denies protection for the mentally impaired, as required by the Eighth Amendment.

This week, Georgia issued a warrant to execute Warren Lee Hill Jr., a death-row inmate convicted of murder, who has an I.Q. of 70. The Georgia Board of Pardons and Paroles is the fail-safe in the state’s criminal justice system, with a mandate to exercise mercy when the court system has failed to come to a just result. That is clearly true in this case. The trial judge found that Mr. Hill was mentally retarded by applying the fairer “preponderance of the evidence” standard in determining his mental impairment.

The State Supreme Court, however, ruled that Mr. Hill had to prove his mental retardation beyond a reasonable doubt. The dissent rightly argued that applying the tougher standard is unconstitutional because it imposes too high a risk that a court’s conclusion will be wrong. The dissent relied on the United States Supreme Court holding that it is unconstitutional to require a defendant to prove that he is incompetent to stand trial by any standard higher than a preponderance of the evidence.