Ever since President Obama proposed holding terrorism detainees without trial, the debate over preventive detention has been growing. Now, NPR has the first look at a detailed legislative proposal to hold detainees indefinitely. The document comes from two experts outside of government, and it is already being discussed in the Obama administration. In a speech last month at the National Archives, President Obama opened the door to the possibility that some terrorism detainees will neither be tried nor released. "If and when we determine the United States must hold individuals to keep them from carrying out an act of war," he said, "we will do so within a system that involves judicial and congressional oversight."

Some conservatives say it will turn the battlefield into CSI: Afghanistan, requiring soldiers to collect evidence as they're being shot at. Some liberals say holding people without trial is fundamentally un-American. "I think most concerns that most people express on the left and right are legitimate concerns," says Wittes. "One problem that I have with the debate over this is that people aren't careful enough to acknowledge that these issues are really hard and that most concerns expressed are legitimate to some degree."

In the first phase of detention, the president could pick up anyone who fits those criteria and hold the person for 14 days. If the president wanted to hold the person longer, a judge would have to approve. The detainee would have an attorney and hearsay evidence could be used against him, though not evidence obtained through coercion. If a judge is persuaded that the detainee is a threat, the president could hold the detainee for six months. At the end of six months, the president could go back to the court and repeat the process. Effectively, Wittes concedes, someone could be locked up forever as long as a court approves of the detention twice a year.