At least 82 death row inmates are seeking reprieves in states that recently banned executing the mentally retarded, an inkling of the hundreds that would likely challenge their sentences if the U.S. Supreme Court finds such executions are unconstitutional.

That means roughly one in 10 inmates sought to get off death row because of mental retardation in states where that option became available last year. Some who seek a national ban say the real number of retarded inmates nationally could be twice that, or 20 percent.

Prosecutors say the system already keeps the mentally retarded off death row, and argue a flat-out ban would spur a slew of groundless appeals.

At the murky intersection where the mentally retarded meet the criminal justice system, advocates and prosecutors square off with much unknown -- how many retarded people are caught in the system and whether they fare worse with police or judges than others.

What seems obvious is that if the high court's decision creates a ban, hundreds of cases will be headed back to court.

With 2,455 inmates on death row in the 20 states that allow executions of the mentally retarded, that would mean 245 potential challenges if 10 percent sought reprieves, or 490 if 20 percent did. Nationally, there were just over 3,700 condemned inmates at the beginning of 2002, according to the Death Penalty Information Center.

Growing bans

The states that prohibit executions of the mentally retarded have jumped from two to 18 since the court's 1989 decision permitting such executions, and at least six more are now considering bans.

In five states that banned such executions last year, at least 82 new challenges have been or will soon be filed claiming mental retardation, defense attorneys estimate conservatively. With a total of 822 death row inmates in those states, that's one in 10.

Nearly half the claims came in North Carolina, the only state that made the ban retroactive so those already condemned to death could seek a reprieve. Elsewhere, defense attorneys estimated there were, or would be, at least 28 claims in Florida, 12 in Arizona, two in Missouri and none in Connecticut.

Georgia banned executions of the mentally retarded in 1988, and a year later its Supreme Court extended the ban to those already waiting on its death row.

Of 102 inmates awaiting execution in 1989, 27 claimed mental retardation, according to Georgia officials.

Seven of those inmates got reprieves from the death penalty -- one when a jury agreed on a finding of mental retardation, two through pardons and four through plea agreements that left them with life sentences.

Three inmates' claims were rejected by juries, one withdrew his claim, one died before resolution and 15 more are still pending.

"It's a tough thing to sort out," said longtime Georgia death penalty lawyer Steve Bayliss. "Our clients, virtually to a man, were raised in environments that were conducive to developing mental retardation" -- poverty, poor nutrition, alcoholism, drug abuse.

Mental retardation is a condition defined by significantly diminished intellectual ability, usually determined by IQs of about 70; problems with adaptive behavior like holding a job or caring for oneself; and the appearance of symptoms or diagnosis as a child.

Prosecutors in the 20 states that allow such executions say enough safeguards already exist to protect the retarded. In less clear-cut cases, a murderer with low intelligence and poor social skills still deserves punishment, they say.

"I don't think a state is going to execute a severely retarded person, and I think they're highly unlikely to execute someone who is in this gray area," said Alabama Attorney General Bill Pryor.

"But if it does happen even there, it's because there have been some very powerful reasons for it" -- like the gravity of the crime and the suspect's ability to understand right and wrong, he said.