A U.S. District Court judge said yesterday he will allow inmates at the D.C. Jail to be doubled up in their cells to ease overcrowding there. At the same time, Judge William B. Bryant restricted the time that inmates can be confined together and ordered that additional guards be placed in those areas.

Bryant, citing expert views that doubling up threatens to dehumanize and punish inmates -- most of whom are awaiting trial -- warned D.C. corrections officials that the overcrowded conditions will not be relieved unless long-range plans are formulated.

Bryant said in his order, however, that he was deferring to the judgment of department officials who told him that doubling up was the "lesser evil" to the current situation at the jail, where inmates are now housed in gymnasiums, recreation areas and dayrooms.

Bryant has retained control over any substantive changes in housing at the jail under the terms of an inmate lawsuit first brought to the federal court in 1971. His decision comes two weeks after corrections officials and attorneys for the inmates appeared at a hearing in Bryant's court to argue the merits of doubling up.

There were 2,167 prisoners in the jail earlier this week, according to corrections officials. That is a record for the facility, which is designed to hold 1,356 inmates. Yesterday's population was 2,160, 600 more than a year ago.

Jail officials estimate that they are housing about 250 prisoners who should be held at Lorton Reformatory, but that 2,300-bed institution is full. The jail was opened in Southeast Washington in 1976 as the modern solution to the overcrowded, century-old jail located nearby.

George E. Holland, acting director of the D.C. Corrections Department, who with other officials has said that the current makeshift dormitory setup is a security risk, said yesterday that Bryant's decision "gives us a little better opportunity to control our situation. That makes us feel a little more confortable."

Holland said that he expected to begin on Monday to fit cells originally intended for one inmate with bunk beds.

J. Patrick Hickey, who represents the jail inmates, said yesterday that he would ask Bryant to modify his order to make sure that jail officials carefully screen inmates for compatability before they are designated cellmates. Hickey had argued that corrections officials had ignored other housing alternatives in favor of doubling up so that officials could save money.

In his order yesterday, Bryant told the corrections department that no pretrial detainee can be housed in this way for more than 12 hours a day and that the situation cannot last more than 30 days. That will require officials to rotate inmates.

To comply with the 12-hour restriction, Bryant said that one cellmate could be removed to another area of the institution, such as a recreation center or dayroom. Bryant said he was imposing those conditions to make sure that inmates are not "unlawfully confined under conditions amounting to punishment."

Bryant, who has been harshly critical of the corrections department's approach to overcrowding, said that the restrictions will act as "relief valves to bleed off some of the pressure" that will inevitably come with doubling up.

There had been testimony before Bryant's ruling that doubling up intensifies friction among inmates accustomed to single cells and intent on preserving their own territory.

In his ruling, Bryant noted that the Supreme Court held in 1978 that the basic constitutional requirement is that pretrial detainees must not be subjected to conditions that amount to punishment. The court set aside arguments supporting the notion of "one-man, one-cell" principle.

The high court said that whether living conditions amount to punishment should be determined on a case-by-case basis, Bryant noted.

Last March, Bryant turned down an initial request from corrections officials to temporarily double up at the jail, a ruling that he vacated yesterday.

Yesterday, Holland said in an interview that doubling up in cells "isn't the ideal situation."

A spokesman for the Virginia Department of Corrections said yesterday that inmates are currently doubled up in newly opened prisons, and that others will be doubled up in institutions scheduled to open in the future. In Maryland, lawsuits are pending in courts challenging the state's practice of doubling up inmates.