The Bush Administration thinks so. Two American citizens, accused of crimes in Iraq and held by US forces, are slated to be handed over to Iraqi authorities - where they would face the death penalty. According to Anabel Lee of the American Prospect's TAPPED blog:

Both men have been detained by the United States in Iraq for more than two years without judicial review or due process. Omar had moved to Iraq looking for work as a contract worker in construction; since being seized in 2004, he has been held in Abu Ghraib and other U.S. detention facilities. The U.S. government has also said it wants to transfer Omar over to Iraqi authorities to be tried. Such a transfer is likely to result in torture and death. Munaf was seized by U.S. military officers in Iraq in 2005 while working as a translator for Romanian journalists. American authorities brought Munaf before an Iraqi court, which swiftly convicted him and sentenced him to death. That conviction has since been reversed.

The US government claims that because they are part of the "coalition of the willing," the normal, constitutional rules for treatment simply don't apply here. That because Omar and Munaf were unlucky enough to be seized by US forces in Iraq, rather than US forces in, say, Tahiti, the US can't possible be responsible for treating them constitutionally.

These two men are being representated by the Brennan Center for Justice in upcoming Supreme Court cases, Geren v. Omar and Munaf v. Geren. You can follow the court filings on their website.