So what's the big deal about habeas corpus? And who cares whether the Guantánamo detainees have this right or not?
The ability to file a writ of habeas corpus is the right of a detained individual to challenge the rationale for his or her detention...essentially, it's the right to demand that the case surrounding the detention be brought to trial. The Bush Administration has argued that this right does not extend to Gitmo detainees...partially because they're not U.S. citizens but rather illegal enemy combatants, and partially because the U.S. Navy base at Guantánamo Bay is not U.S. soil. A less generous characterization of this policy would be "I'm The Decider, and I say that we don't have to give these mopes a fair trial, 'cause they tried to kill Americans."
The problem with this is that it undermines the basic legal right enshrined in the U.S. Constitution for even the vilest criminal to have access to a fair trial. I'm not defending the detainees, or even questioning the rightness of their detention. However much I might despise their actions, though, I still want them to have their day in court. That way, when we convict them, we can say that they're objectively guilty as the result of a legitimate legal process, not just victims of a kangaroo court fueled by righteous patriotic vengeance.
The War on Terror isn't just about blowing stuff up in Afghanistan. It's also about preserving and expanding the rights and liberties that have made life in the U.S. the envy of the world. When we sacrifice our core values for the sake of vengeance, our enemies win.