McCarthy, a former U.S. government terrorist prosecutor, also notes that before Bush became president, both the Washington Post and the New York Times editorialized against giving such "unlawful combatants" the status of POWs. Both approved President Ronald Reagan's 1987 decision not to sign "Protocol I," an addendum to Geneva specifically designed to extend to terrorists the Conventions' prohibition against coercive interrogations.

The Geneva Conventions are treaties, and treaties apply only to states that have signed them. You can't conclude they were meant to benefit non-state terrorist organizations unless you also believe there is no meaningful distinction between al-Qaeda and the French Resistance (as some critics of the Bush administration do indeed insist).

McCarthy elaborates: "[T]errorists cannot opt into Geneva. They fall outside because, by definition, they reject its minimum humanitarian requirements. Affording them Geneva's benefits rewards their savagery and undermines the system's civilizing objectives."

It is absurd to suggest that America can prevail in a war against terrorists by prosecuting them after they carry out attacks in which they intend to die. A rational government, conscious of its duty to protect the population, must attempt to prevent and pre-empt terrorists from completing their missions. That requires gathering solid, actionable intelligence.

"The best source of such intelligence is the interrogation of captured terrorists," McCarthy writes. "Applying the steep Geneva interrogation restrictions reserved for honorable combatants would be suicidal: Life-saving intelligence would be lost and no reciprocal benefit achieved for captured Americans, whom terrorists would torture and kill in any event."

It's of little consequence what Obama thinks of Bush. What is important is that not discard policies that are working, and that he grasps McCarthy's central point: Domestic and international law needs to be reshaped into "tools that work against terrorists, rather than for them." The Geneva Conventions are not a suicide pact. If there are free historians in the future, they will understand that.