The Justice Department, in a dramatic policy reversal, yesterday announced it wants to lend a hand to some states that seek to lift court-imposed limits on their prison populations.

Attorney General William P. Barr said in a speech in Palm Springs, Calif., that some courts went beyond upholding prisoners' constitutional rights and have denied states badly needed beds for violent criminals. But prison rights groups immediately criticized his decision, saying it paves the way for inhumane prisons and increases the threat of violent outbreaks.

Most states, as well as the District, operate at least one prison under court orders governing population size or other conditions. The Justice Department itself pressed for court supervision in three states and two territories -- examples that helped attorneys for inmates win consent decrees in other states.

The new policy to attack some decrees marks the second time in two weeks Barr has moved to address violent crime, considered a potential political problem for President Bush as he seeks reelection. Last week, Barr announced the reassignment of 300 FBI agents from espionage investigations to violent crime cases.

"The choice is clear," Barr told the California District Attorneys Association. "More prison space or more crime."

Barr said the Constitution requires only that inmates not be subjected to cruel and unusual punishment, although Elizabeth Alexander, associate director of the National Prison Project, said the Supreme Court has held that consent decrees can go beyond federal law.

A number of the consent decrees, Barr said, are overly broad, "specifying the particulars of prisoners' diets, exercise, visitation rights and health care. Most burdensome of all, these decrees imposed limitations or caps on the population of state prisons," he said.

Justice Department officials said squeezing in more inmates will not necessarily lead to more prison violence and cited the federal prison system as an example of how a system can be well run even when overcrowded. The federal system operates at 165 percent of its designed capacity, while state prisons average about 115 percent of capacity. California's is the most overcrowded, at 168 percent of capacity.

"If state prisons could operate at the same level as federal prisons," Barr said, "that would mean an additional 286,000 inmate beds, which translates into a savings of $13 billion in construction costs."

Prisoner rights groups estimated that some or all of the prisons in 45 states now operate under court orders, most of which include population caps. The Justice Department estimates consent decrees govern prisons in fewer than 35 states. The department itself helped obtain court orders in Texas, California, Michigan, Guam, the Virgin Islands and three local jails, officials said.

Department officials said the Justice Department will not initiate action to lift the court orders, but will help states that try to do so as long as inmates' constitutional rights remain protected.

Rep. Don Edwards (D-Calif.), who heads the House Judiciary subcommittee on civil and constitutional rights, called the new policy misguided.

Alexander, of the National Prison Project, said, "This is another round of Willie Horton . . . reflecting the plummetting status of the president with the New Hampshire primary coming. . . . We are talking about two people spending often up to 23, 24 hours a day in a space that is about the size of the average American bathroom," she said.

Barr, in justifying the new policy, cited the Supreme Court's ruling in June that prisoners who file lawsuits over inhumane living conditions must show prison officials exhibited "deliberate indifference" to their rights, Justice Department officials said.

In a 5 to 4 decision, the justices said prisoners must not only show conditions are so egregious as to violate the Constitution, but also prove that prison officials knew about the problems and did not make adequate efforts to alleviate them.

Only last year, the Justice Department joined with the American Civil Liberties Union to contend that courts should focus on the conditions, not officials' intent.