Attorneys for inmates of the U.S. Penitentiary at Marion asked an appeals court Friday to end the prison's 4{-year lockdown, arguing that inmates are suffering physical and psychological brutality. ``Prisoners are chained to their beds, spread-eagle, sometimes for days at a time,'' attorney Nancy Horgan argued before a three-judge panel of the 7th U.S. Circuit Court of Appeals. U.S. District Judge James Foreman, who heard the original class-action lawsuit filed on behalf of Marion inmates, refused last February to grant an injunction ending the lockdown. Foreman's ruling followed a 1985 decision by U.S. Magistrate Kenneth Meyers that tight security at the prison dubbed the ``new Alcatraz'' did not constitute cruel and unusual punishment and was necessary to protect inmates and staff. The lockdown was imposed in October 1983, following a bloody week in which two guards and an inmate were killed in separate incidents. Since then, virtually all 350 inmates at the maximum-security penitentiary remain locked in 7-by-8-foot cells for 23 hours a day, although prisoners in certain tiers are given an additional four hours outside their cell each week. Family contact visits aren't allowed. Meals are delivered through a slot and are eaten by prisoners while sitting on the floor or on a bed because cells have no chairs or tables. Attorneys for the inmates argued Friday that the lockdown has become a permanent condition of imprisonment, and that Marion officials use a capricious, arbitrary system in assigning prisoners to tiers and doling out limited privileges. Prison officials counter that the lockdown is necessary because the prison houses the most unmanageable inmates in the federal prison system. ``Most of them come from the segregation units at other federal prisons,'' Assistant U.S. Attorney Ralph Friederich told the judges. ``It is a place for inmates who have demonstrated an inability to control their conduct at other institutions.'' Marion was built in 1963. In 1979, it was designated by the federal Bureau of Prisons as the first Level 6 prison _ the system's most secure. It remains the only Level 6 institution. The roster of high-profile inmates who have been imprisoned there and several spectacular escape attempts have led to its comparison to Alcatraz, the fortress island prison in San Francisco Bay that was closed 25 years ago. Before Friday's hearing, about 50 demonstrators marched outside the federal building in support of the inmates, carrying signs reading ``Prison System Built on Lies.'' Stephen Wittman, a spokesman for the Committee to End the Marion Lockdown, which helped organize the demonstration and has provided legal and financial support to the legal case, contended the penitentiary was being used to silence political prisoners. ``They keep them as long as (they) can and each time we draw attention to an individual, they transfer them,'' he said. ``Equally important, they hold Marion over the head of all prisoners in the system,'' Wittman contended. ``They use the prospect of going to Marion to intimidate them into behaving the way they want them to.''