The New York Times sums up the Zacarias Moussaoui situation perfectly in its Monday editorial:

Allowing the government to deny access to Mr. bin al-Shibh with impunity would set the dangerous precedent that important constitutional rights can be taken away in terrorism cases. It is not at all clear that allowing Mr. Moussaoui to question Mr. bin al-Shibh in carefully monitored circumstances would threaten national security. If the Justice Department is convinced it would, it can adjust the charges against Mr. Moussaoui so Mr. bin al-Shibh's testimony is no longer necessary.

The government has put Judge Brinkema in a bind by suggesting that if it does not like her rulings it will simply transfer Mr. Moussaoui's case to a military tribunal. Tribunals must not become an end run around two centuries of constitutional law. And in any case, it is far from certain that the Supreme Court would allow tribunals to convict people without according them the rights guaranteed by the Sixth Amendment. The war on terrorism has not repealed the Constitution, and Judge Brinkema must ensure that it applies fully in Mr. Moussaoui's case.

Update: Elaine Cassel has more on why the Government is putting up such a ruckus about Moussaoui while not (as yet) transferring him to military custody, including this thought:

The government is counting on the 4th Circuit Court of Appeals, the very-right leaning review court that is likely to agree with the government, to overrule Brinkema, forcing her to throw out the Constitution as her guidebook whenever the government says it is irrelevant.