"He's always supported the idea that you should be able to nevertheless detain people indefinitely as combatants, " said Padmanabhan, now a professor at Vanderbilt Law School.
Vijay Padmanabhan, who was a State Department lawyer responsible for Guantanamo-related cases in the Bush administration, said Obama faces three major questions to achieve his goal of shutting Guantanamo.
Padmanabhan said Obama needs to figure out what level of risk he's willing to accept in Yemen, come up with a strategy for prosecuting detainees and determine how to handle those who are considered dangerous but for whom there isn't sufficient evidence for prosecution.