District Mayor Marion Barry, facing a July 1 deadline to relieve overcrowding at three Occoquan prison facilities, prevailed on the D.C. Council last night to grant him broad new powers to free prisoners to meet court-ordered population limits.

The measure, which passed on a 6-to-4 vote of the council, would allow Barry to declare a state of emergency whenever the prison system's overall population exceeds its official capacity for 30 consecutive days. At that time, the D.C. Department of Corrections would be authorized to reduce some inmates' sentences by 90 days, making them eligible for early parole.

If the sentence reductions do not bring the population down to mandated levels, the legislation would allow the corrections director to grant a second 90-day sentence reduction to some prisoners.

Inmates serving life sentences or terms for convictions of homicide, rape, extortion, assault with a dangerous weapon and other serious crimes would not be eligible for sentence reduction under the measure.

"What remains basically are nonviolent offenders," said council member Wilhemina Rolark (D-Ward 8), who sponsored the emergency legislation at Barry's request.

In a letter sent to Rolark yesterday, Barry said that without the early-parole provision "there is no chance that {the court-imposed} cap can be achieved."

The District's prison population, Barry wrote, has been increasing by almost 150 inmates a month in recent months. The emergency law, which becomes effective immediately, would allow for the release of up to 252 inmates in 180 days, according to Barry's analysis.

The city operates the D.C. Jail in Southeast Washington and nine prison facilities, including the three Occoquan units at the Lorton Reformatory in Fairfax County.

"We are redoubling our efforts to address the District prison overcrowding crisis," Barry said in the letter. "But if the District's prison population continues to increase, it will be impossible to comply with existing population limits."

Legal experts involved in the two sides of the overcrowding controversy disagreed on how much good Barry's new plan will do.

"It's a pressure release valve on the jail population," said J. Patrick Hickey, the lawyer who has represented jail inmates in a 16-year-old overcrowding suit. "Presumably the parole board will still refuse to parole people who are thought to be dangerous."

Clendon H. Lee Jr., a spokesman for the U.S. attorney's office, said the office opposes the measure. "We have said many times that a civilized society owes its citizens an assurance that criminal offenders who should be incarcerated are incarcerated for the full term of the sentences that are imposed," he said. "Data provided by the District of Columbia government indicates that almost all prison inmates are repeat offenders sentenced for felony violations."

Several council members took issue with the proposal as well. Council member Nadine Winter (D-Ward 6) said that some nonviolent offenders should serve their full sentences, and Betty Ann Kane (D-At Large) said that she has "serious doubts" that there are enough nonviolent offenders in the prison system who would be eligible for release.

"This is a . . . very, very broad brush and very heavy-handed approach to a problem, and it's not going to solve the problem," said Kane.

A number of states, including Texas, Florida and Oklahoma, have enacted similar measures.

Last night's action represents the latest step in a continuing controversy that has pitted the District government against the courts for 16 years. District officials have said that court-ordered population limits undermine the city's criminal justice system and that the overcrowding is caused by overzealous sentencing by Superior Court judges.

Corrections Director Hallem Williams stressed that the Rolark bill is not viewed "as the answer to the overcrowding problem in the District of Columbia."

"We see the need to continue to increase halfway house beds, increase the capacity of the prison system and . . . to look at the sentencing issue," he said. "Don't isolate this piece {of legislation} as the District's response to overcrowding."

According to D.C. government statistics filed in a report to the court Monday, 1,953 prisoners are at the three Occoquan facilities, 672 more than permitted under an order by U.S. District Judge June Green. The deadline for enforcement of the order is July 1.

Rolark, in a memorandum sent to council members along with the hurriedly drafted legislation, said yesterday that immediate action was needed or "the District would lose control over how prisoners are to be released."

A status report on prison overcrowding is being prepared for Green's review by retired D.C. Superior Court judge John D. Fauntleroy, who has served as Barry's prisons adviser and was appointed by Green last month as a special court officer to review the overcrowding situation.

Last month, Green was sharply critical of city efforts, saying that the city had not "made the first effort" to reduce the prison population.Staff writer Nancy Lewis contributed to this report.