Under the most aggressive reading of existing law, the government’s war powers extend only to individuals who have joined or substantially supported al Qaeda or an associated force. Without such a connection, Tsarnaev’s military detention was a non-starter.

But even if there had been evidence that Tsarnaev had acted on behalf of al Qaeda, military detention would have been just as misguided.  

In the first years after the 9/11 attacks, the Bush administration twice placed terrorism suspects arrested in the United States in military custody based on their connections to al Qaeda. One case involved a U.S. citizen, Jose Padilla, the other a foreign national, Ali al-Marri. (I represented al-Marri in his legal challenge to his military detention). Both cases generated intense controversy, eventually reaching the Supreme Court. Each time, the government backed down, charged the suspects criminally, and transferred them to civilian custody to avoid an adverse ruling on the scope of its military detention power. The government recognized that even before a Court generally willing to defer to the president’s claims of national security, domestic military detention was a bridge too far. Each time, the transfers led to convictions and ended the legal controversy surrounding their treatment.

Although President Obama has approved the continued military detention of terrorism suspects at Guantanamo, he has drawn a line at the United States. The president recognizes that using the military to detain individuals arrested inside the country — no matter how grave the offense — runs counter to America’s traditions. As CIA director and former top counter-terrorism advisor John Brennan explained, “Our military does not patrol our streets or enforce our laws—nor should it.” 

The Boston bombings illustrate the logic behind this approach. Like other cases of domestic terrorism, the investigation was conducted from start to finish by law enforcement officials. Soldiers played no role, nor should they have, as the case involved core police functions, and not combat against an enemy military force. 

The deliberate attack against innocent people at a public event is a crime worthy of the severest condemnation and punishment. But it is not an act of war. To conclude otherwise not only contradicts international standards, which require an organized enemy force and fighting of sufficient intensity and duration to qualify as an armed conflict. It also eviscerates any meaningful distinction between war and peace, putting the country in a permanent state of war against anyone who resorts to terrorism.

Senator Lindsey GrahamLindsey Olin GrahamSenate panel advances three spending bills Trump says he will sign executive order to end family separations Trump backs narrow bill halting family separations: official MORE (R-S.C.) and other proponents of military detention nevertheless maintain that treating suspects as enemy combatants facilitates interrogations and provides critical intelligence. But as a recent report by an independent, non-partisan task force shows, the real effect of militarizing detention after 9/11 was widespread torture and other abuse, not better intelligence.

Prosecuting terrorism suspects as criminals, on the other hand, can lead to valuable information. Contrary to popular stereotypes, providing defendants with access to lawyers often proves the best way to gain their cooperation, as lawyers encourage them to negotiate deals to obtain a more lenient sentence, particularly where the government’s case is strong.

The Obama administration, moreover, has broadly interpreted the “public safety” exception to the Miranda warnings given to individuals when they are taken into custody. The warnings, which inform suspects they have the right to remain silent and to an attorney, are an important prophylactic against coercion.   The administration has read the exception to allow law enforcement to dispense with Miranda warnings in terrorism cases to gain “timely and valuable intelligence,” even where that information is “not related to any immediate threat,” as the public safety exception ordinarily requires. While an expansive reading of the exception does increase the risk of more coerce interrogations, it also undermines the argument for military detention by giving law enforcement greater latitude to question terrorism suspects.

Senator Graham and other adherents of the wartime approach want to send a message that suspected terrorists are not entitled to the same protections as run-of-the-mill criminals. They seek to express society’s outrage at terrorist acts by altering how we treat the perpetrators — labeling them combatants rather than criminals and denying them the right to a trial. 

The surest way to express society’s collective condemnation, however, is to charge suspected perpetrators with a crime, obtain a conviction, and mete out a sentence, all in manner that guarantees due process of law. Militarizing terrorism detentions accomplishes the exact opposite. Cases inevitably become mired in legal and political controversy, inhibiting the exercise of collective judgment and shifting the focus to the illegitimacy of the process rather than keeping it where belongs — on the commission of the crime itself.

Hafetz is a professor at Seton Hall University School of Law. He is the author, most recently, of “Habeas Corpus after 9/11: Confronting America’s New Global Detention System,” and has represented several terrorism suspects detained as enemy combatants.