Orin is right to criticize Phil's canard-crushing post . Either Boumediene will result in substantive review of the military's detention decisions, or it will not. If not, then nothing has changed. If so, then courts will sometimes correctly overturn mistaken decisions to detain and will sometimes incorrectly overturn correct decisions to detain. (The contrary view — that courts make no mistakes — is not worth addressing.) The first type of outcome will result in nondangerous people going free; the second type of outcome will result in dangerous people going free. We already know that the military has set free dangerous people, and we also know that it has detained nondangerous people for a significant amount of time. As Orin points out, courts can't stop the military from releasing nondangerous people; the courts will focus only on the people that the military seeks to detain. Unless courts defer to the military's judgment, judges will release some of these people — and if judges make errors, as they do, they will release some dangerous people in addition to releasing some nondangerous people.
Many people talk as though the military would like nothing better than to incarcerate the entire populations of Afghanistan and Iraq. In fact, the military faces enormous logistic costs and gains nothing by detaining people who are not dangerous. So the military already has incentives to release the nondangerous and to detain the dangerous. Whether these incentives are adequate is impossible to say. It might be that the military doesn't put enough weight on the moral harm of detaining the nondangerous. It is possible that civilian judges will take that harm more seriously. It is also possible that civilian judges will overweight that harm, demanding an excessively high standard that results in the release of too many dangerous people. This is Scalia's concern; he overstates his case, but it is perfectly reasonable.
Finally, Phil conjectures that Gitmo radicalizes detainees, making them more likely to engage in terrorism if they are released. He seems to have in mind people who are not already radical but who are picked up incorrectly, yet people who are sufficiently inclined to violence that unfair treatment will push them over the edge. I suspect that if there are people in this category, they are not going to be mollified much by having a habeas proceeding. Once you start detaining and releasing people, you run the risk that they will be radicalized; this is just one of many costs — one suspects a pretty trivial one, next to the others that the detention regime creates. Ordinary law enforcement accepts this cost — we don't have a zero error rate for incarceration of suspected criminals even though we know that some people might be radicalized in prison. It is a cost that the military itself has every reason to take account of, without the need of habeas proceedings.