As a society, we have failed miserably to find a way to deal appropriately and humanely with mentally retarded adults. And we've failed miserably in Georgia prisons: Witness Hays State Prison in Trion, where inmates have roamed the halls like gang mobs.

Put the two failures together and we find an urgent example right now on Georgia's death row where we have a mentally retarded man set to die by lethal injection on Friday -- despite the fact that his mental disability makes him constitutionally ineligible for execution.

Unless the U.S. Supreme Court steps in to stop it, the state will execute Warren Lee Hill Jr., whose IQ is 70. His mental capacity peaked at the development of a sixth-grader, according to experts and his attorney.

In 2002, the Supreme Court ruled in Atkins v. Virginia that it is cruel and unusual punishment to execute a mentally retarded person because such persons "do not act with the level of moral culpability that characterizes the most serious adult criminal conduct."

But in Georgia, an inmate is required to prove his mental retardation beyond a reasonable doubt. And Georgia's threshold is the highest in the nation.

In Hill's case, every medical examining expert agrees he is mentally retarded, including the state's own experts. But they first testified against Hill and only later admitted that their testimony was wrong because they were inexperienced and "rushed."

Clinical experts say Georgia's burden of proof is virtually impossible to meet, especially for persons who are "mildly mentally retarded," such as Hill. Adults with 70 IQs may be able to read and write, or obtain a driver's license, yet still qualify as mentally retarded under the clinical definition. To a jury and even many judges, however, such abilities can make it difficult to find mental retardation "beyond a reasonable doubt."

The appeals court rejected the revised mental evaluation opinions.

But what really keeps Hill on death row, ironically, is the restrictive terms of an anti-terroism law. Passed by Congress in 1996, the Anti-terroism and Effective Death Penalty Act limits the rights of criminal defendants by prohibiting prisoners from filing more than one petition challenging violation of their constitutional rights, even in cases where they have an indisputable claim, according to Lindsay C. Harrison, an attorney who submitted an amicus brief in support of Hill's original petition. Harrison wrote an opinion letter about Hill for USA Today that was published earlier this week when Hill was expected to be executed on Monday.

The appeals court said Hill's appeal did not fit the restrictive terms of that 1996 act because new evidence must raise doubt as to guilt, rather than the appropriateness of the punishment.

Hill, 52, received a temporary death reprieve from Monday until Friday when attorneys raised questions about a law prohibiting the release of information involving Georgia's execution drug supply.

Make no mistake about it: Hill killed a man. He is on death row for the 1990 Lee County killing of fellow inmate, Joseph Handspike. Before that, Hill was given a life sentence for shooting his 18-year-old girlfriend 11 times in 1986 in Cobb County, according to Georgia officials. Authorities say Hill attacked Handspike as he slept, beating him to death with a board.

The family of Joseph Handspike has said Mr. Hill should not be executed.

This region's own experience with state prison control at Hays State Prison at Trion should show what might have prompted a mentally retarded and very malleable inmate's attack on Handspike.

Gangs have ruled the prison there -- to the point that families of inmates were being extorted for money lest their loved one be targeted and killed. Cellphones -- though banned -- proliferated. Cell doors were broken for more than two years. Not a week went by without a stabbing or beating. Three inmates were killed there in a month, and a fourth was killed during transport to another facility.

Mentally retarded adults would either be prey or tools in such a mainstream prison. Though they are difficult to deal with, their special needs mean they don't belong there.

And they certainly don't belong on death row. Would a sixth-grader belong there?

The fact that Georgia and this nation seem loathe or unable to unscramble the unintended consequences of our laws is no reason to ignore the Constitution's responsibility to the least among us.

We urge the Supreme Court to stop Georgia's madness.