05/10/2011 06:10 pm ET Updated Jul 10, 2011

Are Terrorists Beyond the Law?

While Osama bin Laden contributes to the great chain of life in some undisclosed corner of the Arabian Sea, his deputy Khalid Sheikh Mohammed awaits trial. Perhaps unbeknownst to himself, he has just been promoted. Now comes the hard part.

The undeniable risk of taking bin Laden alive, and holding him for prosecution, was enough for President Obama to suspend due process in a hail of sniper fire. This may have been necessary, and few would question the president's claim that "justice was done." But as a former law professor, Mr. Obama is aware those words have a specific meaning. Applying them to the midnight assassination of an unarmed man -- however heinous his crimes -- raises a chilling question: can we ever "do justice" to terrorists?

We are about to find out. There is no escaping justice for Khalid Sheikh Mohammed, the architect of 9/11. Not for Mr. Mohammed, and not for the United States. Last month, Attorney General Eric Holder bowed to political pressure to abandon a federal trial for Mohammed. The defendant will not face open justice on the site of his alleged crimes, but the star chamber of an offshore military tribunal. That decision must be considered anew.

At the Nuremberg tribunals in 1945, Justice Robert Jackson commended the Allies for "staying the hand of vengeance" against the Nazis, in the face of intense political and social pressure. On May 1, 2011, the hand of vengeance came down hard. What matters is not whether this was the right decision, an issue best left for future historians, but what happens next.

Commentators derided New York federal court as a potential media circus, a show trial. But show trials are not merely those in which the state directs the outcome. They can also demonstrate some essential quality of the state itself. Given the defendant's new status as Public Enemy No. 1, the Mohammed case is destined to become the greatest show trial of the early 21st century. As Adolf Eichmann embodied the horrors of the Holocaust in 1961, Khalid Sheikh Mohammed will now be the face of September 11, 2001. An American court will determine whether terrorists are ordinary felons or enemy combatants, both, or neither. The answer will irrevocably shape US policy.

Thus the choice of courts is not a procedural question, or even a legal one. It is a question of ethics. Can we afford to give due process to Khalid Sheikh Mohammed? Can we deny it to him? On this decision we ourselves will be judged -- by our peers, by our enemies, by history. For the first time since Nuremberg, the law itself is on trial. If our legal system cannot sustain the prosecution of a murderer for his crimes, the implications for our society and its laws are catastrophic. We shall have reached a precipice, and as an historian myself I can think only of the ancient cartographer who, confronted by the trackless unknown, drew a boundary and beyond it wrote "hic draconis." Here be dragons.

Our leaders know this. Advocates for military court are not cynical or cruel, and they make a decent case. Mr. Mohammed is not an ordinary criminal, and the nature of his crime transcends felony. There is no injustice in recognizing this fact, and tailoring the venue to suit the circumstances. Moreover the security risk of a federal trial, in this new post-Osama age, is perhaps even greater. As a New Yorker myself, I am not immune to this argument. As someone who has also lost a loved one to a terrorist attack, I am no less committed to seeing justice done.

The problem, though, is that a military trial will give terrorist organizations the legitimacy they crave, and must not achieve. How can Al Qaeda win? Only by gaining recognition not just for its cause, but for itself. To term the defendant a murderer may be reductive, but it is accurate. To term him an enemy combatant is to give spurious credence to his cause. If we cannot distinguish between a terrorist organization and a state it is we who must change, for Al Qaeda will not.

Great cases, said Oliver Wendell Holmes Jr., make bad law. But some cases are so great that they cannot help but be remembered. For good or ill, the trial of Khalid Sheikh Mohammed will be a lasting testament to our law, and to ourselves.