That drew a vehement dissent from the court's three most conservative members.
In two one-paragraph orders, the Supreme Court ordered Texas not to execute Curtis Moore and Brian Davis while the justices decide whether to review their cases.
In effect, the high court was putting the Texas cases on hold until it rules later this month -- in the case of a Virginia death row inmate -- on whether execution of the mentally retarded violates the Eighth Amendment's ban on cruel and unusual punishment.
Each member of the Supreme Court oversees courts in the 12 geographical circuits of the United States.
Justice Antonin Scalia oversees courts in the 5th U.S. Circuit, which is comprised of Texas, Mississippi and Louisiana.
The two condemned Texas prisoners therefore sent their emergency requests for stays of execution to Scalia. As is his custom, Scalia sent the requests on to the full court for a vote.
In each of the two cases, "the court disrupts the state's criminal process to entertain a last-minute claim ... that was not raised previously at trial, or in extensive proceedings for (state and federal) review," Scalia said. "Indeed, in each case even the factual predicate for the new claim (mental retardation) had not been asserted at trial -- and in Davis's case had not been asserted even in subsequent proceedings, right up until the day of scheduled execution. The court's action is unprecedented."
Scalia pointed out that Moore was convicted of participating in three brutal killings during the course of a drug deal and robbery.
"One victim was stuffed in the trunk of a car, shot, doused with gasoline and lit afire," the justice said. "The second victim was driven to his girlfriend's home, where he and the third victim, the girlfriend, were shot dead."
Scalia said Moore had been tested when he was 12 and showed an IQ of 68, within the mildly retarded range. But a pretrial test showed he had an IQ of 76, within the normal range.
Moore was convicted and sentenced in 1996.
Davis was convicted and sentenced to death in 1992 for killing during the course of a robbery.
"The mentally retarded victim was found in his ransacked apartment with a swastika drawn on his abdomen and 11 stab wounds to his neck, chest and back," Scalia said.
The inmate's executions were stayed by the Supreme Court only until the justices decide whether to review their case.
It takes a vote of at least five of the nine justices to grant an emergency stay. It takes a vote of at least four justices to accept a case for review.
(Application No. 01-834, Moore vs. Texas; and 01-853, Davis vs. Texas)