WASHINGTON: Former US president George W. Bush's top law enforcer John Ashcroft could be sued and be held personally responsible for the wrongful detention of a US "terror" witness, a federal court of appeals said.

Placing responsibility on the shoulders of US officials in the Bush administration, and specifically Ashcroft, who was attorney general at the time, the judge at the ninth circuit court of appeals in Boise, Idaho ruled in favor of Abdullah al-Kidd, an American citizen who brought the complaint.

The "aggressive detention of lawbreakers and material witnesses is vital to preventing, disrupting or delaying new attacks," Ashcroft said at the time, in a statement quoted in court.

The decision Friday, however, came after a 2006 ruling that found material witness law could only be employed when an individual is genuinely sought as a witness and there was a flight risk; not to be used as a preventive action.

Arrested on March 16, 2003 at Washington's Dulles Airport, al-Kidd was held for 13 months in maximum security prisons. Officials wanted to use him as a witness in the trial of another suspect in the investigation on the September 11th, 2001 attacks, Sami Omar al-Hussayen.

Material witness charges against Al-Kidd were eventually dropped and he was never called to testify in court.

His case stems from losing potential employment because of his security history and the legal complaint against Ashcroft's efforts to "preventively" detain or investigate suspects.

Judge Milan Smith, writing for the court's majority decisions, said that those who wrote the US Constitution "would have disapproved of the arrest, detention, and harsh confinement of a United States citizen as a 'material witness' under the circumstances, and for the immediate purpose alleged..."

"Sadly," Smith wrote, "some confidently assert that the government has the power to arrest and detain or restrict American citizens for months on end, in sometimes primitive conditions."

In such circumstances, he wrote, such powers were used "not because there is evidence that they have committed a crime, but merely because the government wishes to investigate them for possible wrongdoing, or to prevent them from having contact with others in the outside world."

The court, said attorney Lee Gelernt, who argued the appeal, "made it very clear today that former attorney general Ashcroft's use of the federal material witness law circumvented the Constitution."