THE CHARGING OF BOSTON bombing suspect Dzhokhar Tsarnaev on Monday put to an end, as a practical matter, an incipient debate about whether he should be held and questioned as an “enemy combatant.” That’s just as well, because it wasn’t a very intelligent discussion.

Republican Sens. John McCain (Ariz.) and Lindsey O. Graham (S.C.) began calling for Mr. Tsarnaev’s transfer to military detention on Friday night, saying, “It is absolutely vital the suspect be questioned for intelligence-gathering purposes” and that “the least of our worries is a criminal trial which will likely be held years from now.”

The first statement reflects a reasonable concern but can be managed by other legal means. The second is breathtakingly shortsighted. It will, in fact, matter greatly whether Mr. Tsarnaev, if he survives his injuries, is held accountable for his alleged crimes — and that the United States is seen by the world as capable of responding to a serious terrorist attack under the rule of law. The Bush administration’s failure to respect the Geneva Conventions and the U.N. Convention against Torture following the attacks of Sept. 11, 2001, not only gravely damaged U.S. prestige but also gave autocrats around the world an excuse to flout human rights standards in their own pursuit of “terrorism,” real or concocted.

We have supported the use of military detention for foreign terrorism suspects captured abroad. But in Mr. Tsarnaev’s case, such a transfer would have been illegal. As Benjamin Wittes of the Brookings Institution has pointed out, Congress has authorized military detention only for militants who are “part of” or “substantially” supporting al-Qaeda or the Taliban. No evidence has surfaced that Mr. Tsarnaev had such connections; even if he did, his status as a U.S. citizen arrested in the United States means that his detention by the military would be subject to challenge on constitutional grounds.

And even if military detention were legal, there is no practical reason to remove Mr. Tsarnaev from the criminal justice system. The evidence against him appears overwhelming, and the federal charges lodged against him Monday, which include using a weapon of mass destruction, could lead to a death sentence. By contrast, the military tribunal system created to try al-Qaeda suspects at Guantanamo Bay has bogged down, with the shameful result that Khalid Sheik Mohammed and other architects of the 9/11 attacks have yet to be found guilty or held accountable.

On Friday evening, there was legitimate reason for concern that Mr. Tsarnaev might have information about further attacks or accomplices still at large. However, it would not have been necessary to transfer him to military custody to question him about such matters without advising him of his Miranda rights and providing him with legal representation. Supreme Court case law provides a “public safety” exception to normal interrogation rules, and the FBI has interpreted this as giving it relatively broad authority to question terrorism suspects before they are informed of their Miranda rights.

In Mr. Tsarnaev’s case, it is not clear that meaningful questioning was possible before his arraignment Monday. But if he recovers from his wounds, U.S. authorities should have sufficient leverage to obtain Mr. Tsarnaev’s cooperation by conventional — and legal — means.