Rupert Cornwell: Will the US at last admit it executed an innocent man?

Out of America: The case of Cameron Todd Willingham, put to death five years ago, could mark a turning point for American justice

A year or two ago, Antonin Scalia wrote an opinion on the constitutionality of America's death penalty in the pithy language that makes him simultaneously the most maddeningly conservative, yet the most quotable and entertaining, of the nine current justices of the United States Supreme Court.

Long had he scoured the records, but he was aware of "not a single case – not one – in which it is clear that a person was executed for a crime he did not commit." If such a miscarriage of justice had occurred in recent years, Scalia went on, "we would not have to hunt for it; the innocent's name would be shouted from the rooftops". Well, it's time to get the ladder out.

In February 2004, Cameron Todd Willingham was put to death by the state of Texas for the arson/murder of his three young daughters. They had been trapped in their home when it went up in flames two days before Christmas in 1991. A fortnight later, Willingham, an unemployed car mechanic, was arrested and charged with having deliberately set the fire. His trial had the all too familiar shortcomings when a defendant is poor: lousy, state-appointed defence lawyers, dubious but unchallenged evidence peddled by a couple of supposed forensic experts, and the testimony of a jail snitch who claimed Willingham had confessed to the crime in an unguarded moment while awaiting trial. Proceedings lasted only two days, and the jury took just an hour to find him guilty.

After many unavailing appeals – the last of them to the Texas Board of Pardons and Paroles which did not even bother to consider a report by the country's leading fire investigator concluding that in all probability the fire was accidental – Willingham was executed by lethal injection in the infamous prison at Huntsville. To the very end, strapped to the gurney in the death chamber, he protested his innocence: "I have been persecuted for 12 years for something I did not do."

Ever since, the case has been a focus of death penalty opponents here. As long ago as December 2004, The Chicago Tribune carried a long article casting doubt on the fire investigators' evidence at the 1992 trial. CNN later did a piece to the same effect, while three separate outside reports – including one commissioned by the state of Texas – reached similar conclusions.

This month however came the most devastating blow of all: 16,000 words of measured prose in The New Yorker magazine that took a wrecking ball to the entire case against Willingham. The snitch, it turns out, was a drug-sodden petty criminal who later recanted his evidence. "The statute of limitations on perjury has run on perjury, hasn't it?", he asked David Grann, the magazine's reporter.

Nor, he notes, was any credible motive for the crime ever established. Willingham was no saint. He drank, he had affairs, and was prone to violence. At the trial prosecutors suggested he had killed his children "because they got in the way of his beer". His wife, Stacy, said that nothing unusual had happened before the fire, however, and that while her husband had treated her badly on occasion, he had never abused the children: "They were spoiled rotten." Nor was a big insurance payout on the cards.

But Grann's fiercest demolition job was on the scientific evidence for arson, without which Willingham, for all his personal failings, was guilty of no crime whatsoever. Retracing the tragic affair with various experts, including Gerald Hurst whose January 2004 report was ignored by the Texas Pardons Board, the author demonstrated that not one of the 20 alleged signs of arson cited at the trial stood up to serious scientific scrutiny.

In short there was, according to Grann, "not a single shred of evidence of arson", merely the folklore and old wives tales about fires and arson handed down from one generation of police and investigators to the next. Even Craig Beyler, the eminent fire scientist hired by the Texas state commission, wrote that the original investigators had thrown "rational reasoning" to the wind, and relied on methods "characteristic of mystics or psychics." In other words, Willingham had been a victim of that scourge of American courtrooms, junk science.

Oddly, but somehow fittingly, this new interest in what seems ever more certainly a terrible miscarriage of American justice coincides with the 25th anniversary of the discovery by the British scientist Sir Alec Jeffreys of DNA fingerprinting – the technique which has established the guilt or innocence of countless criminals, including not a few on the death rows of the US. Clearly, DNA testing could not have settled the argument over Willingham's guilt, and the doubts about his conviction, while grave, do not have the black-or-white irrefutability of DNA evidence. But they're starting to come close.

The commission's final report on the Willingham case is due next year. Thus it may just be that Texas, the state most addicted to capital punishment, will be the one that finally proves Justice Scalia wrong, and admits that it had indeed carried out "the execution of a legally and factually innocent person".

In another section of the opinion in which he asserted such events never happened, Scalia also took a swipe at the Popes, foreign civil rights advocates, handwringing European liberals and do-gooders (not to mention tedious articles like this one in overseas newspapers) who might venture to disagree. "There exists in some parts of the world sanctimonious criticism of America's death penalty, as somehow unworthy of a civilised society.... Most of the countries to which these finger-waggers belong had the death penalty themselves until recently – and indeed, many of them would still have it if the democratic will prevailed."

But, as even thoroughly American institutions like The New Yorker and The Chicago Tribune have made clear, if the state killing of Cameron Todd Willingham is not unworthy of a civilised society, then what is?