Hope for Carty as court debates death penalty

The latest skirmish in America's ongoing debate over capital punishment will take place in a court in Houston this morning, where lawyers for an accused murderer called John Edward Green will argue that the system has become so unreliable as to be an affront to natural justice.

They are likely to cite the fact that since 1976, when the US restored capital punishment, 136 death row inmates have been exonerated, including at least 12 in Texas.

At least one man has already been wrongfully put to death by the Lone Star State: last month, DNA testing revealed that a single hair used to convict Claude Howard Jones, who was executed for murdering a shop assistant in 1999, came not from him – as the jury had originally been told – but from the victim.

The innocence of another executed man is meanwhile the subject of heated debate. Cameron Todd Willingham was executed in 2004 after being convicted of starting a fire that killed his three daughters. But forensic experts have recently claimed that he was innocent, and that prosecutors obscured crucial evidence during his trial.

An official inquiry into his case by the Texas Forensic Science Commission will report next month. Its members have already admitted that there were serious "flaws" in Willingham's treatment.

Linda Carty's treatment at the hands of the Texan legal system is also said to have been riddled with basic errors. Carty, who emigrated to the US in the early 1980s to attend university, has always claimed British citizenship due to being born and raised on the Caribbean island of St Kitts. Under the Vienna Convention, UK authorities should therefore have immediately been informed of her arrest in 2001.

Had this happened, the Foreign Office would have been able to supply Carty with a competent legal team. But St Kitts failed to fulfil its legal obligation to contact the British Consulate in Houston. Paul Lynch, the current Consul General, said: "There was an appalling failure by her lawyer and the fact that we weren't notified meant that we were not able to give her support. I do not believe that justice was ever done."

Carty's court-appointed defence lawyer never mentioned she had spent years as an informant for the US Drug Enforcement Agency, failed to call defence witnesses and neglected to ask basic questions of prosecution ones. Detectives were never asked, for example, why they never took fingerprints and DNA samples from the body of the victim.

During one of Carty's appeals, Judge Vanessa D Gilmore, a federal trial judge acknowledged her conviction was "a harsh result", but said that an incompetent defence lawyer was not grounds for a retrial.

* Because of a production error, the number of exhonerated inmates in the second paragraph was quoted as 21,136, rather than 136, in the early version.