President Obama's advisers have been drafting an executive order that would set up a system for periodically reviewing the cases of Guantanamo prisoners whom courts have approved for detention without trial, officials said. The proposal would replace the "annual review boards" that the Bush administration had used to revisit its decision to hold each prisoner. Under that system, which the Obama administration shut down, a panel of military officers periodically reviewed the accusations against and talked to each prisoner who wanted to participate. The prisoners were not represented by lawyers. Officers then decided whether a prisoner was still a threat...