The U.S. military is beginning legal proceedings at Guantanamo Bay, Cuba to review whether nearly 600 detainees being held there fall under the category of enemy combatants. The hearings are the first step in what could either lead to detainees being released or ultimately tried for war crimes.

All of the nearly 600 detainees still being held at Guantanamo, some for nearly three years, will have the opportunity to contest their designation as enemy combatants in the process that opens Friday.

Overseeing it is Navy Secretary Gordon England, who says if detainees convince what the Pentagon says will be a neutral panel of three U.S. military officers that they have been wrongly detained, they will be free to return to their home country.

"This is an administrative proceeding, fact-based administrative proceeding to determine if they are or are not enemy combatants. This is not a trial," said Mr. England.

The hearings are in part a response to last month's Supreme Court ruling that declared detainees picked up on the battlefield in Afghanistan and suspected of supporting al-Qaida have the right to contest their status as enemy combatants.

"The plan is to have three tribunal teams and, optimistically, we are hoping that each team can conduct 24 tribunals a week," he added. "And our planning is to complete the tribunals, have them totally complete within 30 to 120 days."

Guantanamo detainees will be assigned a military-appointed representative to help in preparing their cases. But they will not have access to a lawyer, leading legal and human rights groups to denounce the process as unfair.

"These tribunals are seriously flawed," said Human Rights Watch spokesman Eric Goldstein. "They are not set up to be impartial and they severely limit the ability of detainees to make their claims. Also, they are predicated on the Pentagon's belief, which is legally wrong, that all enemy combatants at Guantanamo can still be held under the rules of war."

If detainees chose to waive the review process, as the Pentagon says some already have, their detention cases would be considered by the tribunal anyway. Those determined to be enemy combatants could still challenge their detentions in U.S. civilian court if they chose to, with legal representation.