Unless we can save him, Troy Davis, 38, will die on Tuesday at 7pm (midnight BST). The state of Georgia will execute him by lethal injection for the murder of a police officer in 1989. The trouble is, three of the four witnesses who testified at his trial have recanted. Meanwhile two other witnesses who say Davis confessed to them have done likewise. They say they made their statements under pressure from the police. But the courts refuse to hear them. The Atlanta Journal-Constitution has argued for a pause to examine the new evidence in an editorial.

So too has the former FBI director under Ronald Reagan and the first George Bush, William Sessions. "There is no more serious violent crime than the murder of an off-duty police officer who was putting his life on the line to protect innocent bystanders," he argued in an Atlanta Journal-Constitution commentary. But "serious questions have been raised about Davis' guilt ... It would be intolerable to execute an innocent man."

The murder took place in the early hours of the morning at a Burger King near the Savannah bus station on August 19, 1989. A fight over a beer between a homeless man called Larry Young and another man got out of hand when an off-duty police officer, Mark MacPhail, who was moonlighting as a security guard, tried to break it up. Before he could get out his gun the man who was arguing with Larry Young had shot him in the chest and the face.

With no gun and no physical evidence at hand everything turned on witnesses. Troy Davis was in the Burger King, along with many others. But the man many say actually did the shooting came to the police and said Troy did it. The police then tracked down witnesses and, allegedly, strong-armed them into saying the same thing.

Troy was convicted in 1991. His family tried in vain to find lawyers who would represent him at appeal but the Georgia Resource Centre, which had been representing him, had had 70% of its budget cut. By the time they found a pro-bono lawyer the courts said it was too late. Their reasoning emerges not from some Bush II era civil rights infringement but courtesy of a law passed by Bill Clinton in the wake of the Okalahoma City bombing, which restricts federal courts in their ability to overturn death penalty convictions.

There are three things that are clear from Davis' case. The first is that the American legal system does not administer blind justice. Lady Liberty will open her eyes for cash. Had he been wealthy - or just wealthier - he could have bought a defence in time that would have effectively challenged the case.

Second is that these laws passed in the wake of terrorist attacks have far-reaching consequences beyond those initially intended. They weaken all of our rights and in so doing could threaten any of us at any time.

Finally, that the death penalty is a barbaric practice that has no place in the 21st century, let alone in a nation that seeks to hold up its values and practices as a global standard.

Time is running out for Troy. And so are our options. Amnesty International has set up an action centre to do what we can to save his life. Troy has just 24 hours left to live - surely you can spare a few minutes.

UPDATE: Georgia's board of parole and pardons has granted a stay of execution for Troy Davis for 90 days, until October 14, in order to hear more about the case.