A first hearing in front of prospective jurors was barely two minutes underway when Judge Leonie Brinkema ordered marshals to remove the 37-year-old Frenchman back to his cell following a verbal outburst.
"This trial is a circus," said Moussaoui, dressed in a green jumpsuit with "Prisoner" emblazoned on the back, as he was led from the court after the first of three court appearances.
Less than an hour later Moussaoui, the only man charged over the September 11, 2001 attacks, was ejected from a separate courtroom after another show of defiance.
The trial is starting with the selection of a jury to decide if Moussaoui should face the death penalty, or life in prison, for his role in the attacks which killed almost three thousand people.
Moussaoui, who has admitted six charges of conspiring with al-Qaeda, again rejected his defence team -- appointed by Ms Brinkema in November 2003, after she withdrew his right to represent himself after a string of previous disruptions.
"They are not my lawyers. I don't want them to represent me. I'm al-Qaeda; they are American; they are my enemies," he said in court.
Judge Brinkema repeatedly warned Moussaoui his behavior would see him sent back to the cells, but he talked over her, in a loud voice, contemptuous of the court, yet calm and in control.
The trial opened with four separate hearings, each comprising about 125 jury candidates, at the start of a process which will produce a 12-person panel, and six alternates for the trial's opening arguments on March 6.
In his third appearance of the day, Moussaoui vowed he would testify in the trial.
"For four years, I have waited. I will take the stand," he said.
"I will tell the truth I know, this defence team is a fraud. They are lying from top to end."
After each outburst, Moussaoui put his hands on his head, to show he was not resisting his expulsion, and shuffled out of court led by guards.
The hearings were held amid tight security around the court in the Washington suburb of Alexandria, Virginia. Bomb sniffing dogs search the bags of potential jurors, roads were closed off, and armed police patrolled the courthouse and nearby apartment blocks.
Jury selection
Ms Brinkema told jurors that if they were adversely affected by Moussaoui's theatrics, they should note it on a 49 page questionnaire intended to weed out unsuitable jurors.
She also warned them they must put aside their haunting memories of the attacks on New York and Washington, which left about 3,000 dead, to ensure Moussaoui, gets a fair trial.
"Persons on trial must be judged not on the basis of what is in the news or popular media, but rather on the hard evidence presented in the courtroom during the trial," she said.
In his plea last year, Moussaoui said al-Qaeda leader bin Laden had told him to fly a plane into the White House, but as part of a follow up wave of attacks to the strikes on the Pentagon and World Trade Centre in New York.
He was detained in August 2001 and prosecutors, who are seeking the death penalty, want to prove that he deliberately witheld details of the attacks.
This final phase of the Moussaoui prosecution is likely to see relatives of September 11 victims testify in a bid to bolster the prosecution case that Moussaoui should get the death penalty.
Jurors will be first asked to rule on whether Moussaoui deliberately lied about his knowledge of the planned attacks, and is therefore eligible to be put to death.
Secondly they would have to decide if he should be sentenced to death.
His lawyers look set to argue that their client is mentally ill and so should not face the death penalty.
The US government wants a death penalty for Moussaoui, who was arrested in Minnesota on August 16, 2001, after overstaying his visa and arousing suspicion at a flight training school.
Trial ‘not fair’
The detainee's mother has attacked the US judiciary for the way her son is being handled.
"Zacarias is an ideal culprit because he is poor, educated and Arab," the mother, Aicha el-Wafi, told AFP in the French city of Montpellier.
"My son is refusing to speak to the lawyers or to the defence because he sees that there is no way out, that the prosecutor wants a culprit and that there is no way to defend himself.
"My son is an extremist. He should be judged for that -- but not for the things he did not do. He did not take part in the September 11 attacks," she said.
Born in France in May 1968, Moussaoui studied economics in Montpellier and obtained a degree in management at South Bank university in London in 1995.
Ms Brinkema has imposed strict rules on the media for the case, heavily restricting the extent to which jurors can be photographed.
She told potential jurors on Monday that they faced an "awesome responsibility" in deliberating on Moussaoui's fate, and told them to avoid newspapers and television news reports until they know if they will be needed.