Nothing makes a citizenry, or a faction of the citizenry, angrier than when the nation's unlected highest court makes a decision with which they disagree. However, Supreme Court decisions must be criticized in a cautious and moderate way, an independent judiciary being necessary to the maintenance of freedom in any democratic system of government. Not having studied law, much less constitutional law, I am also hesitant to criticize the decisions of five justices who are among the most intelligent and thoughtful law experts available in this country.
But everyone else is doing it, so why not give it a shot? George Will's main objections to the critics are that there have been worse decisions, the majority justices are intelligent people, the decision is to provide only the right to request a hearing, and the right of habeas corpus is important to the restraint of governmental power. All of these are true, but they are also irrelevant in different degrees.
The habeas right is very important in the restriction of government, but it has never before been applied to prisoners of war and/or non-citizens. To do so makes little sense. Even granting that POWs and non-citizens have this right, the Constitution provides for a suspension of the habeas right for just such a time as this. The fact that five intelligent Supreme Court justices made this decision is no defense, considering that four also opposed it vehemently. Seven justices were responsible for the disastrous Roe case. The fact that the case provides merely the right to request a hearing, and not a hearing per se, will serve to moderate the consequences of this ruling, it's true, but the right to request a hearing is still a right to a hearing, provided one chooses the right court. (And there's always a sympathetic court.) It does not change the fact that people who have never been accorded Constitutional rights, and with good reason, have been accorded Constitutional rights in a way that will have serious negative consequences for our nation's security.
George Will does make one other point--that military tribunals allow hearsay evidence and evidence produced under compulsion. Well, they aren't courts who hear the cases of citizens charged with committing a crime. They're courts designed to deal with cases having to do with military personnel and prisoners of war, and thus have proper jurisdiction over the detainees at Gitmo. What's more, their fairness is well attested.
The result of this decision will not be more humane treatment of prisoners of war. (And, despite mythology still prevalent today, the Guantanamo Bay facility is one of the most humane holding facilities in the history of warfare.) Instead, such prisoners will be shipped secretly to other nations for imprisonment and interrogation by far less civilized means, or they will simply be interrogated and killed quickly.