In Hamdi's case, the court ruled that, while the detention itself was authorized by the Authorization for the Use of Military Force (AUMF), Hamdi still has the right to challenge his detention and contest the facts against him. Quoting Foucha v. Louisiana "Freedom from bodily restraint has always been at the core of the liberty protected by the Due Process Clause from arbitrary governmental action." I think a quote by Herbert Packer, former Professor of Law at Stanford University, from his book "The Limits of Criminal Sanction" also is very pertinent:
"The combination of stigma and loss of liberty...is viewed as being the heaviest deprivation that government can inflict on the individual. Furthermore, the processes that culminate in these highly afflictive sanctions are seen as in themselves coercive, restrictive, and demeaning. Power is always subject to abuse-sometimes subtle, othertimes...open and ugly. Precisely because of its potency in subjecting the individual to the coercive power of the state, the criminal process must...be subjected to controls that prevent it from operating at maximal efficiency.
Though clearly the government has a compelling interest to protect the United States from aggressors and detain those who cause us harm, the court remarked that "as critical as the Government's interest may be in detaining those who actually pose an immediate threat to the national security of the United States during ongoing international conflict, history and common sense teach us that an unchecked system of detention carries the potential to become a means for oppression and abuse of others who do not present that sort of threat." The court, in my view, struck the proper balance, holding that the executive can detain enemy combatants but still has some obligation to prove in an adversarial setting that they fit within that category. This is especially important in Mr. Hamdi's case, as his father claims he was in Afghanistan for humanitarian aid purposes, and was not in Afghanistan for long enough to receive military training (we haven't heard from Mr. Hamdi himself because he is being held incommunicado by the government). Perhaps former Chief Justice Earl Warren put it best in US v. Robel, "It would indeed be ironic if, in the name of national defense, we would sanction the subversion of one of those liberties which makes the defense of the Nation worthwhile."
The second set of cases (referred to collectively as the Rasul case) deals with the jurisdiction of American courts to here challenges from Guantanamo Bay detainees of their detention. This case is in certain ways more important than Hamdi, as unlike in Hamdi the prior precedent seemed to lean against the detainees. In the 1950 Supreme Court case Johnson v. Eisentrager, the court dealt with a case brought by German citizens captured in China, convicted of War Crimes in Nanking, and incarcerated in occupied post-war Germany. The court ruled that as these areas all fell outside of US jurisdiction, there was no standing to sue in that case. In that case, the court remarked that:
We are here confronted with a decision whose basic premise is that these prisoners are entitled, as a constitutional right, to sue in some court of the United States for a writ of habeas corpus. To support that assumption we must hold that a prisoner of our military authorities is constitutionally entitled to the writ, even though he (a) is an enemy alien; (b) has never been or resided in the United States; (c) was captured outside of our territory and there held in military custody as a prisoner of war; (d) was tried and convicted by a Military Commission sitting outside the United States; (e) for offenses against laws of war committed outside the United States; (f) and is at all times imprisoned outside the United States, and concluded that no right to habeas corpus existing in such a situation.
In Rasul, Justice Stevens distinguished from Eisentrager on several grounds:
Petitioners in these cases differ from the Eisentrager detainees in important respects: They are not nationals of countries at war with the United States, and they deny that they have engaged in or plotted acts of aggression against the United States; they have never been afforded access to any tribunal, much less charged with and convicted of wrongdoing; and for more than two years they have been imprisoned in territory over which the United States exercises exclusive jurisdiction and control.
Furthermore, the court noted that Eisentrager had been modified significantly by following decisions. In Braden v. 30th Judicial Circuit Court of Kentucky, the court made a core revision to how it viewed Habeas Corpus claims. It now held that the writ acted on the person holding the prisoner, rather than the prisoner himself. Thus, since the people who were responsible for the detention of the prisoners in Guantanamo were within the jurisdiction of US courts, the prisoners now had standing to sue where such law did not exist at the time of the Eisentrager decision.
What's important to note in both of these cases is what they DON'T do. They don't prevent the president from detaining illegal combatants. They expressly cast aside the possibility of wars conducted under the threat of litigation. The courts holding in these cases is limited only to forcing the US to ascertain that those they imprison have committed a crime. In making these rulings, the courts put an important check on the President's power to bypass the court system and the bill of rights under the pretext of national security.