Washington is consumed once more with the problem of terrorism, driven by the dual pressures of an unsuccessful terrorist attack on commercial aviation and upcoming elections that give politicians an incentive to speak in terms of war. We are again treated to the ridiculous argument that a terrorist attack is either an act of war or a criminal violation but never both. Senators McCain and Lieberman recently proposed a bill that mandates military detention for domestic terror suspects instead of civilian criminal justice proceedings — an approach that sidelines half of our domestic counterterrorism tools.

The Enemy Belligerent, Interrogation, Detention, and Prosecution Act of 2010 would use military detention to incapacitate suspected terrorists. Choosing military detention over prosecution takes criminal justice tools off the table, including prosecuting terrorists for the instrumentalities of terrorism — assembling bombs, financing, and all of the illegal activities associated with attacking the system.

We’ve been down this road before, and domestic military detention in lieu of criminal prosecution has not worked as advertised.

Take the case of Ali Saleh Mohamed Kahlah al-Marri. After the 9/11 attacks, the FBI arrested al-Marri, an exchange student at Bradley University in Peoria, Illinois. The government alleged that al-Marri met with Osama Bin Laden, was working with senior al Qaeda organizers, had a more-than-casual interest in poisons, and was told by his handlers to be in America before September 11th or to forget about executing his mission here.

Terrorism, even when it can be viewed as an act of war perpetrated by a sleeper agent such as al-Marri, inherently breaks laws. Al-Marri arrived in the United States with a suitcase full of credit card numbers and set up a false business entity and bank accounts to finance his mission.

The government produced a seven-count indictment that, if proven, would have put al-Marri away for a long time. The charges included fraudulent use of a false identity (five or fifteen years, depending on the amount of money involved), three counts of bank fraud (thirty years each for a total of 90 years), making false statements to FBI investigators (ten years), and credit card fraud (ten years). This amounts to a maximum sentence of 115 or 125 years in federal prison. Subsequent sentence enhancers for committing these crimes in support of an act of international terrorism make the same indictment worth up to 146 years today.

That’s an impressive prison stretch, but it wasn’t too late for the government to snatch defeat from the jaws of victory.

Before al-Marri’s trial, the government removed him to military custody and asked that the charges against him be dismissed with prejudice (meaning that they cannot be re-filed upon his release). He remained in a naval brig in South Carolina as lawyers fought over his continued detention without trial. No military commission was ever planned for al-Marri. This was a power play to establish the precedent that terrorism suspects could be held indefinitely without trial, and the government asserted at oral argument before the 4th Circuit that the process al-Marri received is what any American citizen would receive.

The Supreme Court agreed to review his case, prompting the Obama administration to move al-Marri back to the civilian criminal justice system in early 2009. The government re-indicted al-Marri on two counts of material support of terrorism (maximum sentence of thirty years). He pleaded guilty to one count and received eight years. The judge was barred from officially giving credit for time served in military custody, but a fifteen-year sentence minus six years and change for being in military custody is what he received.

The al-Marri case was not a success. He should have been locked up for the rest of his life, but cramming a set of civilian crimes into a case for military detention failed to protect national security and provide justice.

The McCain-Lieberman proposal would have pushed al-Marri’s trial into a military commission. As they stand now, our military commissions have jurisdiction over material support of terrorism but not the panoply of federal statutes that allow prosecution of the instrumentalities of terrorism. The Founders allowed Congress to punish war crimes –- “Offenses against the Law of Nations” –- and bank fraud does not fit the bill. Congress could add a catch-all provision to the commissions’ statute, but do we really want military officers sitting in judgment of domestic financial crimes?

Many terrorist acts are simultaneously acts of war and criminal violations, and applying one legal paradigm to the exclusion of the other makes for good politics but terrible policy. The United States should continue to use its criminal justice tools. Conservatives have been railing for years about limits on the Executive during wartime; passing this bill would certainly tie the Executive’s hands. If you can get 146 years, take it. We can defeat al Qaeda both on the battlefield and in the courtroom.