THE 20TH HIJACKER….Zacarias Moussaoui, the “20th hijacker,” was arrested prior to 9/11 on immigration charges. He had been taking flying lessons throughout 2001 and has admitted to being an al-Qaeda member. And although he adamantly denies that he was involved in the 9/11 hijackings, the government says he was.

Is he guilty? Maybe. But since it’s not a sure thing by any stretch, Moussaoui ought to have a chance to prove his innocence.

Today, however, concluding a long-running dispute, the government refused a judge’s final order ? upheld by an appellate court ? to allow Moussaoui to call a witness in his defense: Ramzi bin al-Shibh, the self-described planner of the 9/11 attacks, who is currently being held in an undisclosed location overseas. bin al-Shibh is critical to Moussaoui’s defense because the government claims that he’s the one who wired money to Moussaoui and other 9/11 hijackers.

The upshot is that the judge is likely to dismiss the charges against Moussaoui and the government will move the trial to a military tribunal, where the rules are more to their liking.

I understand that the government has legitimate national security concerns here, but it’s still hard for me to believe that this is happening. He might not be guilty, after all, and that’s what a trial is supposed to establish. But if he truly isn’t guilty, how can he possibly prove it if he’s not allowed to call the witnesses that are part of the government’s own case?

This whole thing is way too much like the Salem witch trials for my taste, where guilt is preordained and nothing a defendant can say will prove otherwise. I don’t have much sympathy for Moussaoui, who’s certainly an al-Qaeda terrorist of one kind or another, but considering what we’ve learned lately about the quality of U.S. intelligence in matters like this, I’m also not inclined to simply accept the government’s word that he was a participant in the 9/11 conspiracy. Moussaoui should be allowed a fair trial.