The decision, which involved U.S. citizens held by "American forces under an American chain of command" in Iraq, was unanimous and based on U.S. law.

A Jordanian-U.S. citizen and an Iraqi-U.S. citizen traveled to Iraq and allegedly helped terrorists in operations there. They were eventually captured by U.S.-led coalition forces and U.S. military tribunals determined they were threats to Iraqi security. One was referred to the Iraqi courts for criminal prosecution.

Federal courts in the United States determined that neither could apply for a constitutional review of his case.

But in the unanimous opinion written by John Roberts' title='Chief Justice John Roberts' class='tpstyle'>Chief Justice John Roberts, the Supreme Court said the U.S. habeas corpus statute applies to U.S. citizens held abroad by the U.S. military under the U.S. chain of command, rejecting the government's argument that the nature of the multi-national force meant it didn't apply.

However, the high court said U.S. courts couldn't use the statute to ban the military from transferring prisoners to a foreign prosecution when prisoners committed crimes in that foreign country.

The Supreme Court said approximately 24,000 prisoners of all nationalities are held by the multi-national force but didn't say how many of those were U.S. citizens.

(No. 06-1666, Munaf et al vs. Geren et al)