Washington ? The Justice Department defied a judge Monday and refused to make an al-Qaida witness available to terrorism suspect Zacarias Moussaoui — even though the tactic could lead to dismissal of the case.

Dismissal could ultimately lead to prosecution in a military tribunal.

The high stakes defiance, on national security grounds, allows U.S. District Judge Leonie Brinkema to penalize the government but dismissal is not her only option. The Alexandria, Va.-based judge could throw out some charges, exclude government evidence or instruct jurors that the government refused to provide certain evidence.

The department’s move is likely to trigger intervention by the 4th U.S. Circuit Court of Appeals in Richmond, Va., but not immediately. The full court voted 7-5 on Monday to deny, for now, reconsideration of a three-judge panel’s refusal to step in at this stage.

While the appellate ruling was only procedural at this point, chief Judge William Wilkins warned that the court would not blindly accept government claims of national security in the refusal to produce suspected Sept. 11 coordinator Ramzi Binalshibh.

“Siding with the government in all cases where national security concerns are asserted would entail surrender of the independence of the judicial branch and abandonment of our sworn commitment to uphold the rule of law,” Wilkins said.

The government said it recognized that its objection meant the deposition of Binalshibh couldn’t go forward, and that the decision “obligates the court now to dismiss the indictment unless the court finds that the interests of justice can be served by another action.”

If the court considers an alternative to dismissal, prosecutors asked that they be heard before action is taken. The government also asked Brinkema to postpone any action pending a ruling by the appellate court.

Brinkema has ruled that Moussaoui, who is representing himself, should be allowed to question Binalshibh through a satellite hookup. The exchange, which the government is desperately trying to stop, could be played to jurors if Moussaoui’s case goes to trial.

Brinkema had concluded Binalshibh may support Moussaoui’s contention that he was not part of the 9-11 conspiracy.

U.S. Atty. Gen. John Ashcroft has repeatedly said he wants to continue the prosecution in the civilian court system, although military tribunal rules would make national security paramount over Moussaoui’s constitutional right to have access to a potentially favorable witness.