A number of news outlets reported yesterday that 61 former Guantanamo Bay detainees, or about 11 percent of those who have been released, returned to the battlefield to fight the United States.

While this is distressing, it is not news. The Heritage Foundation has long recognized that any system designed to assess the threat Guantanamo detainees pose to America will never be perfect. The Administrative Review Board system, established in 2004, to assess annually whether each enemy combatant in Guantanamo should be released or transferred always posed some risk. As former Deputy Assistant Defense Secretary for Detainee Affairs and Heritage Senior Legal Fellow Cully Stimson wrote this past summer:

ARBs are a discretionary process not required by the Geneva Conventions, U.S. law, or international law. Unlike any other country at war in the history of the world, the United States decided as a matter of policy to release or transfer combatants from Guantanamo during an ongoing conflict.

This policy decision has risks, as evidenced by the fact that the Pentagon has confirmed that at least 30 former Guantanamo detainees have returned to the fight and taken up arms against the United States and its allies. Many experts believe that number is much higher.

Something to keep in mind as President-elect Barack Obama tries to close Guantanamo permanently.