The American Civil Liberties Union and other human rights groups urged President-elect Obama not to create a special legal system for terror detainees to replace Bush administration's system set up in Guantanamo Bay.

In a letter to Obama, the ACLU, Amnesty International USA, Human Rights First and Human Rights Watch said they "categorically oppose the creation of any other ad-hoc illegal detention system or 'third way'" that would allow the government to hold prisoners without charging them, which the Bush administration has done. Such a system would be "essentially moving Guantanamo on-shore," the groups said.

The Bush administration has argued that the detainees, many of them captured in Afghanistan, aren't U.S. citizens or prisoners of war and thus don't have their legal protections. But the Supreme Court ruled last summer that the military commissions set up by the Bush administration to try detainees are unconstitutional and that the prisoners have the right to bring their cases to U.S. federal court.

Obama has pledged to close Guantanamo prison, but he hasn't said how he will handle the detainees' cases.

Read the civil rights group's full letter to Obama after the jump.

Dear President-elect Obama:

As heads of four prominent civil liberties and human rights organizations, we wish to convey our uniform position on the steps we believe should be taken once you fulfill your pledge to close the Guant