Al-Qaida conspirator Zacarias Moussaoui remains the only person convicted in connection with the September 11, 2001 terrorist attacks. Others who allegedly planned the 9/11 attacks are being held by the U.S. abroad. But as of now, there are no plans to put them on trial.
Moussaoui was sentenced to life in prison after he pled guilty to conspiring with al-Qaida to fly planes into buildings.
But what about some of the alleged planners of the 9/11 attacks now in custody, like Khalid Sheikh Mohammed or Ramzi Binalshibh, who allegedly financed the 19 hijackers on September 11.
U.S. officials say that despite the lengthy and challenging prosecution of Zacarias Moussaoui, criminal prosecution remains an option.
"The Moussaoui case, I think, demonstrates that we can be successful," said Paul McNulty, the deputy U.S. attorney general. "In our investigations, we will continue to use every tool and authority available to us to identify risks at the earliest stage possible. And in deciding whether to prosecute, we will not wait to see what becomes of risks."
During the court proceedings Moussaoui was known for his disruptive outbursts in court and taunting relatives of victims who had testified.
Legal experts and others wonder if the difficulties on display in the Moussaoui case are making it less likely that the government will want to try the alleged masterminds of the 9/11 attacks in open court.
Benjamin Wittes has written editorials about the issue in the Washington Post newspaper. He spoke at a forum on the issue sponsored by the American Enterprise Institute in Washington.
"I mean, these are the people we have identified and are in our custody and there seems to be no plans whatsoever to bring them to trial," said Wittes.
Trying terrorist suspects in open court could be risky because the government might be forced to reveal some of its intelligence sources as it presents evidence. Prosecutors would also have to address whether torture was used to obtain confessions.
Neal Katyal, a law professor at Georgetown University Law Center in Washington, believes the Bush administration would prefer to simply detain some of the terror suspects indefinitely.
"I think the federal courts have given the president a fairly robust power to detain enemy combatants and I think they are likely to continue to do that," said Neal Katyal. "And so, folks like Khalid Sheik Mohammed, I think, are going to be detained indefinitely. And given that backdrop, it seems unwise to bring a prosecution in which the results may be acquittal," he said.
The Bush administration could also decide to try some of the al-Qaida suspects in military commissions, also known as military tribunals.
Professor Katyal represents Salim Ahmed Hamdan, now awaiting trial as an enemy combatant at the U.S. naval base at Guantanamo Bay, Cuba.
Hamdan is challenging the Bush administration's right to try terror suspects through military tribunals before the U.S. Supreme Court.
"And he can sue the President of the United States, the most powerful man on earth, in the highest court of the land," Katyal said. "That is something that in any other country, I think I would have to fear for my life and I think Hamdan would have to fear for his. It is something remarkably American about our system."
The Supreme Court is expected to issue a decision before the end of June on the legality of the military commissions.
While it remains unclear what the United States will do with the alleged high profile al-Qaida members in custody, prosecutions of lower-level suspects continue.
Deputy Attorney General Paul McNulty says since the 9/11 attacks, the Justice Department has secured 253 convictions against 435 defendants in terrorism-related cases. Many of those convictions, however, involved minor crimes and immigration violations not directly related to terrorist acts or plots.