How should a nation committed to the rule of law deal with captured terrorists who are believed to be dangerous but who cannot realistically be brought to trial? This issue has arisen in the context of the debate over whether to close the US prison at Guantanamo Bay, which candidate Barack Obama promised to do, but President Obama has not yet done.

A major reason why Guantanamo remains open is that it contains several detainees — the precise number is unknown — who, if released, would almost certainly return to a life of terrorism. Indeed, some have, and many in detention have overtly stated their malignant intentions. Others have histories that suggest the likelihood of recidivism. But even some of the most dangerous detainees cannot be tried, either because there is insufficient admissible evidence of a specific crime or because the evidence comes from undercover sources the government is unwilling to out. If Guantanamo were to be closed, as it should be, and the detainees transferred to other facilities, the basic problem would still remain.


Similar dilemmas arose in previous wars during which enemy combatants were captured and detained as prisoners of war until the cessation of hostilities, after which they were released without trial. The difference is that the war on terrorism has no predictable termination point, as the current campaign against the Islamic State, or ISIS, demonstrates. Moreover, captured terrorists are not lawful combatants entitled to be treated as POWs. They are unlawful combatants who can, under the laws of war, be tried as ordinary criminals, as some have been. But with regard to those who cannot, there is a Hobson’s choice: either free them and risk renewed terrorism; or continue to detain them indefinitely, despite the absence of a firm legal basis for what could amount to life imprisonment without due process.

Imagine if the masked man who recently beheaded the two American journalists were captured, and a valued ISIS undercover source, who couldn’t testify without blowing his cover, identified him as the killer. What would we do? What should we do?

There is no perfect solution to this problem under existing laws. Some academics have proposed an intermediate solution: Pass a preventive detention law that would afford detainees some semblance of the due process accorded to ordinary criminal defendants, but that would authorize a tribunal to order continued confinement based on evidence of continuing dangerousness.


This is what the United Kingdom did during both world wars and, more relevantly, what Israel does today with regard to captured terrorists during its never-ending conflict with Hamas, Hezbollah, and other terrorist groups. Such a watered-down process might include the right to counsel as well as notice of the charges and the requirement of proof beyond a reasonable doubt. But it would not include the right to confront and cross-examine a witness whose identity would remain secret, or the right to discover evidence that the government does not wish to disclose. The question is not whether this halfway approach to legal rights is a good system — it surely is not — but whether it is better or worse that the current lawless system.

On the positive side, it provides somewhat more visibility and accountability. On the negative side, it accords some degree of legitimacy to a deeply flawed process.

The late Justice Robert Jackson aptly observed that “the most odious of oppressions are those which mask as justice.” There is a legitimate concern that a preventive detention law would provide such a “mask,” because it would provide for the forms of due process without much substance.

This is especially so when a tribunal is empowered to confine based on predictions of future crimes rather than on evidence of past crimes. As Yogi Berra once put it: “Predictions are difficult to make, especially about the future.” Moreover, tribunals will generally choose to err on the side of confinement rather than release. This is because errors resulting in confinement are never disclosed, since the “dangerous” person remains confined and unable to disprove the prediction. Whereas errors resulting in release become public outrages, when the wrongly released person commits an act of terrorism.


It is unlikely, therefore, that many currently detained terrorists would have a different outcome — would actually be released — under the proposed system of watered-down-due-process-preventive-detention. The proposed system might make us feel better, but it would do little to protect their rights.

Another approach might be to impose a time limit on the duration of any confinement without trial. A similar approach has been tried with regard to pretrial detention of ordinary criminal defendants, but so many exceptions have been written into the law that some defendants, charged with ordinary crimes, have been held without trial for as long as five years — perhaps even more.

Another problem is that if there were a time limit, even one as long as 10 years, there would still be some dangerous terrorist masterminds who upon release would endanger our security. Would we be prepared to release after 10 years the masked terrorist who beheaded two American journalists?

Again, the least worst solution to this conundrum may be to require checks and balances, under which all three branches must agree before a person can be detained as a dangerous terrorist. The legislative branch should enact a narrow preventive detention law, with specific criteria and as many rights as are consistent with security. The executive branch should exercise care in deciding who to detain. And the judiciary should serve as a final check on abuses.


This will not eliminate all injustices but will come as close as reasonably possible to complying with the rule of law without exposing innocent people to undue risks of preventable terrorist acts. That may be all that can be expected from a democracy challenged by terrorism.

Alan M. Dershowitz is a professor emeritus at Harvard Law School. His newest e-book, “Terror Tunnels: The Case For Israel’s Just War Against Hamas,’’ has just been published.