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 civilian 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...