A federal appeals court on Tuesday upheld the conviction and life sentence awarded to Zacarias Moussaoui, the only person to stand trial in a US court in the 9/11 attacks.
A three-judge panel of the fourth US Circuit Court of Appeals unanimously rejected Moussaoui's claim that he was denied potentially helpful evidence during his trial and was restricted in choosing his own counsel.
The judges held that the trial was fair and that Moussaoui, 41, deserved life sentence.
The judges found that Moussaoui had not demonstrated that the government withheld "exculpatory material" that would have rescinded the guilty plea and move the case back to trial.
In 2005, the terrorist had pleaded guilty in 2005 to six conspiracy charges in the attack involving the ramming of two planes into the World Trade Centre.
The lawyers for the senior Al Qaeda member argued that he should be resentenced due to a violation of his constitutional rights, but this was rejected by the court.
Moussaoui will serve his sentence in a Colorado prison called Supermax.
During his trial, Moussaoui, who is of Moroccan descent, declared his allegiance to Osama bin Laden but denied having been part of 9/11 that was carried out by 19 terrorists.
Instead, Moussaoui claimed that he was to be part of a fifth plane that was to be rammed into the White House, but that never happened.Moussaoui, who was indicted in 2001, was the only person to stand trial for the 9/11 attack. The trail of another Al Qaeda operative, Khalid Sheikh Mohammad, is still pending.