FACTBOX: Supreme Court case on Guantanamo prison

(Reuters) - The Supreme Court hears arguments on Wednesday in a major case to decide the legal rights of terrorism suspects held in the U.S. detention center at Guantanamo Bay, Cuba.

Following are some facts about the case.

* The Guantanamo prison opened in January 2002 to house prisoners swept up in the U.S.-led invasion of Afghanistan. About 305 detainees are in the camp, according to the Defense Department, and about 470 have been released. Among 14 designated "high-value" detainees are suspected September 11 attack organizer Khalid Sheikh Mohammed.

* The court will consider the constitutionality of the 2006 Military Commissions Act denying Guantanamo inmates "habeas corpus" rights to seek a judicial review of their detention.

* Some inmates, human-rights groups and federal law-enforcement officials have described abusive interrogation and treatment at the prison. The Defense Department says it treats the inmates humanely.

* Among those who have filed briefs with the Supreme Court on the side of Guantanamo inmates are the U.N. High Commissioner for Human Rights, retired U.S. military officers, former federal judges, the American Bar Association, European and British parliament members, Amnesty International and Republican U.S. Sen. Arlen Specter.

* Groups supporting the government's position with briefs include retired U.S. generals and admirals, the Committee on the Present Danger and the American Center for Law and Justice.

* The Supreme Court has twice previously ruled against the government's procedures for holding or trying the detainees. A federal appeals court upheld the 2006 law, but in a highly unusual move, a majority of Supreme Court justices voted to take the case after that had rejected a petition to hear it.

(Writing by Randall Mikkelsen and Paul Grant)