quick question

To paraphrase a subtitle on CNN yesterday: "Three detainees were released from Guantanamo Bay today as the government deemed that they were no longer enemy combatants."

The question is how is it that someone loses their "enemy combatant" status, and how will this affect the viability of military tribunals in light of recent passage of the Military Commissions Act? Developments in the Jose Padilla case may prove illuminating with regard to what increasingly appears to be an arbitrary designation that defies logic, as well as human rights.