Should a man with an IQ of 70 be on death row?

He killed twice, and twice the state of Georgia has attempted to kill him. But for now Warren Hill, 53, is still breathing. His most recent rendezvous with the executioner, at 7pm on Tuesday night, was again averted by the intervention of two courts, with just 30 minutes to go.

But the victory for his lawyers, who argue that their client should be spared the death penalty because he is intellectually impaired, may be fleeting. It remained unclear last night how durable the twin reprieves will be – one court ordered a stay of at least 30 days. If and when they lapse, execution may still come quickly.

Hill had been serving a life sentence for shooting dead his 18-year-old girlfriend when, in 1990, he bludgeoned his prison cellmate to death with a board studded with nails. The second murder earned him a death sentence and last July the state came within 90 minutes of doing the deed before a stay was issued.

On Tuesday it was closer. Just half an hour more and they would have dispatched him by lethal injection. Indeed, attendants had already administered the oral sedative Ativan to calm him before being taken to the death chamber.

One of the stays was from the Georgia Court of Appeals to address concerns about how the death chamber handles the drugs used in lethal injections.

But the 11th US Circuit Court of Appeals, a federal court, took up the issue that has been the main fight of Hill’s lawyers – that he is mentally impaired. He has a recorded IQ of just 70.

A 2002 US Supreme Court ruling outlaws the execution of anyone who does not have their full mental faculties. However, Georgia says it is incumbent on the defendant to prove “mental retardation” and to do so “beyond a reasonable doubt”. No other state with capital punishment on its books sets such a standard.

Brian Kammer, Hill’s lead lawyer, said that in issuing its stay, the federal court ordered “a further briefing on the issue of mental retardation”.

The position of the defence appeared to be bolstered recently after three doctors, who at the time of Hill’s trial said they did not consider him retarded, recanted their testimony, saying that advances in treatment and diagnosis had prompted them to change their minds.

“All the doctors who have examined Mr Hill are unanimous in their diagnosis of mental retardation, so there is no question that his execution would have been in violation of the US Supreme Court’s 2002 ruling,” Mr Kammer said in a statement after the stay was issued.

The case has drawn international attention including from the European Union which had called for clemency. “This case has raised attention around the world, with particular concern around Mr Hill’s intellectual disability,” said Annabelle Malins, the British consul general in Atlanta. Former President Jimmy Carter also issued a statement on Tuesday on behalf of himself and his wife. “Georgia should not violate its own prohibition against executing individuals with serious diminished capacity,” it said.

Demonstrating that Hill qualifies as ‘mentally retarded’ remains the defence’s first challenge. “The state of Georgia remains an extreme outlier in requiring that defendants prove they have mental retardation ‘beyond a reasonable doubt.’ This is the strictest standard in any jurisdiction in the nation,” Mr Kammer said.