"An alien captured and detained within the United States... has a right to habeas corpus protected by the Constitution's Suspension Clause."

A divided panel of the Fourth Circuit interprets the Military Commissions Act not to apply to civilians who are seized within the United States. SCOTUSblog reports:

Under MCA, Judge Motz wrote, ... enemy combatant status must either be determined by a Combatant Status Review Tribunal -- the military administrative panels set up by the Pentagon -- or by some other "Executive tribunal." Neither has made such a ruling as to [Ali Saleh Kahlah] al-Marri, the decision said. (The CSRT panels are operating only for foreign nationals being held at the U.S. military prison camp at Guantanamo Bay, Cuba.)...

The Circuit Court found the government's claim of "inherent" presidential authority to order military detention of civilians to be "breathtaking," and was broad enough even to allow detention of U.S. citizens.

Orin Kerr has more:

The court takes a very narrow view of the category "enemy combatant"; if I read the court correctly, it sees the category as basically limited to the catgeory of military opponent in battle rather than Al-Qaeda terrorist....

According to the Fourth Circuit, this left Al-Marri as a "civilian," and thus entitled to the Due Process protections of anyone lawfully in the United States. In other words, the AUMF just doesn't reach so far as to permit the military to detain a civilian terrorist suspect in the U.S. like Al-Marri.

Kerr predicts the court will be reversed, either by the Fourth Circuit en banc or by the Supreme Court.