FP: If some of these detainees are tried in U.S. courts—people such as Khalid Sheikh Mohammed—how much of their testimony from interrogations using techniques such as waterboarding would be allowed in court?

MW: One of the issues likely to arise in many Guantánamo prosecutions will be allegations of mistreatment and even torture by U.S. personnel. And not only will prosecutions potentially expose some past U.S. conduct, but that conduct might even spoil the chances for a conviction in some cases.

FP: If Guantánamo is closed, what options would you recommend to President-elect Obama for structuring the capture and detainment of future terrorism suspects?

MW: An important point to make is this: The problem of Guantánamo goes beyond the 250 or so individuals currently detained there. The United States will continue to capture, detain, and need to interrogate suspected terrorists long into the future. And the bigger question than whether to hold them at Guantánamo or not is one of legal authority. On what legal basis and according to what standards will the United States conduct detentions? That is a huge issue facing the new president. One of the most important lessons of the Bush years is that any answer to that question ought to be made in close consultation with Congress and with U.S. allies.

FP: How would you describe the legacy of the Bush administration in detention? What did they get right and wrong? Legally speaking, did they end up setting back their own effort?

MW: A strategic error of the Bush administration in the immediate aftermath of Sept. 11 was its overemphasis on operational flexibility and underemphasis on legitimacy. It took legal interpretations in order to maximize its freedom to detain and interrogate without adequately recognizing the dangers to coalition cooperation, U.S. reputation abroad, and legal principles that the United States stands for and promotes.

FP: To paraphrase your old boss, Donald Rumsfeld, are U.S. detention policies currently producing more terrorists than they are removing from the world?

MW: It’s impossible to know. On the one hand, U.S. detention policies play an important role in neutralizing threats and gaining critical intelligence. However, overbroad detention or perceptions of abuse have also no doubt played into the hands of our enemies and undermined support for U.S. operations among key audiences. Looking forward, the critical task of the new administration is to recalibrate detention policy in a way that mitigates all of those dangers.

Matthew Waxman is associate professor at Columbia Law School and adjunct senior fellow for law and foreign policy at the Council on Foreign Relations. He served as deputy assistant secretary of defense for detainee affairs from 2004 to 2005.