The heated second-guessing by conservatives of Attorney General Eric Holder's decision to hold a civilian trial in Manhattan for Khalid Shaikh Mohammed and four others charged as co-conspirators in the 9/11 mass murders is to some extent understandable.

Of course, it's fatuous to rant, as some Republicans do, that a law enforcement response to terrorist war crimes is some kind of illegitimate Democratic invention. The Bush administration combined war-on-terrorism rhetoric with civi-lian criminal prosecutions of would-be shoe-bomber Richard Reid, would-be hijacker Zacarias Moussaoui, and scores of lesser terrorist wannabes. Congress has given the government the options of trying such people in civilian federal courts or by military commissions, or detaining them without charge as enemy combatants. The circumstances dictate which approach makes the most sense in any specific case.

The best choice in this instance is "a tough call," as Holder testified on November 18 to the Senate Judiciary Com-mittee. That's because removing these five defendants from the military commissions where their cases began to a civi-lian federal court in Manhattan will have real costs, as former Attorney General Michael Mukasey and some other se-rious analysts argue.

Specifically, a civilian trial will increase the risk that sensitive national security secrets will spill out. It will give defendants a bigger stage on which to rail about CIA "torture" and demonize America. It will make the judge, prosecu-tors, jurors, and the courthouse targets for terrorists. It could theoretically lead to acquittals or dismissals of charges on technical grounds. And it plays into the loud complaints by human-rights activists that the administration is relegating to second-class justice the terrorist defendants who are still to be tried by military commissions.