The D.C. Board of Parole has approved new rules that in some cases will more than double the amount of prison time it can require parole violators to serve as a penalty for committing a felony crime while on release.

The new regulations are designed to send a message of tougher enforcement to parolees who contemplate new crimes after release from prison, according to parole board sources. Many law enforcement officials contend that chronic repeat offenders are responsible for a significant share of crime in the city.

While lowering penalties for parolees who commit minor parole violations, the new regulations mean that parolees convicted of a felony such as armed robbery while on the streets can be returned to prison to serve a minimum two-year penalty before the parole board will consider allowing them to begin serving time on any new sentences. Under previous regulations, the minimum penalty was about one year.

Officials in the D.C. Department of Corrections and the Public Defender Service complained that the regulations will exacerbate overcrowding problems in the city's prison system.

"This is certain to worsen conditions at prisons that are already overcrowded," Francis D. Carter, director of the Public Defender Service, which provides legal assistance in some criminal cases for people who cannot afford their own lawyers.

George Holland, the city's acting director of correction, said the move may tax the city's detention facilities. "We've got to look at where we've got space, how to shuffle things around a little bit," Holland said. "The community obviously doesn't want inmates out there committing crimes."

The new rules address in a sweeping fashion the extent to which unserved portions of prison sentences can be used as penalties to deter a convict's criminal activity during parole.

At issue is what is commonly referred to as backup time--that portion of a prison sentence not served behind bars but for which a convict can be held accountable while he is outside the prison on parole.

For example, a person sentenced to 18 years in prison for armed robbery might be paroled after serving a minimum six years. The 12 remaining years are the backup time during which he must observe several conditions of release.

If the parolee fails to meet those conditions--by committing another robbery, for instance--the board can revoke his parole and return him to prison, where he would have 12 years of backup time facing him in addition to whatever sentence was imposed for the felony committed while on parole.

Under the old rules, the board could require the parolee to serve a minimum one year of the 12 years backup time before it would permit him to start his sentence for the second robbery. Under the new penalty structure, the parolee would be required to serve as much as two of the 12 years as a minimum penalty.

Only a small percentage of criminals serve their full prison sentences before being released on parole. Of the city's approximately 3,000 parolees in 1980, the most recent year for which parole figures are available, the parole board issued arrest warrants against 581 for parole violations.

Of those, 215 involved technical violations, such as failing to report to a parole officer. The other 366 were for new crimes. The board acted on the warrants by revoking parole--meaning that backup time could have been imposed--in 349 cases, almost 12 percent of all parolees.

Previously, parolees with less than five years backup time faced a minimum six-month penalty--or return to prison--for all violations, ranging from technical violations to committing a felony crime.

Under the new regulations, the penalty remains the same for technical violations, but the minimum for committing a misdemeanor crime, such as shoplifting, has been raised to 6 to 9 months. For a felony crime, such as armed robbery, the new minimum is 9 to 15 months.

Previously, parolees with more than five years backup time faced a minimum 12-month penalty for all violations. Under the new regulations, the minimum penalty for technical violations has been lowered to 6 to 9 months. The new penalty for misdemeanor crimes is 9 to 15 months and for felony convictions, the minimum has been raised to 15 to 24 months.

"What we are trying to do is be more equitable," said parole board chairman Bernice Just, "to match the severity of the penalty to the severity of the parole violation."

The parole board has discretionary powers to set longer penalties, up to the full length of remaining backup time, but rarely does so. In most cases, parolees still have backup time remaining on old convictions when they begin to serve time for new convictions.

This old backup time does not disappear while new sentences are being served. Rather, it acrues with each new conviction and subsequent parole. When parole is revoked, the time a parolee spent on release automatically is erased, meaning he is accountable for all his original backup time.

"We've seen guys who spent 15 years on a five-year sentence," said parole board executive director Barney Shapiro.

While this threat exists, and is stiffened under the new regulations, law enforcement officials acknowledged that in the past it rarely has been more than a threat.

The system did not work, they said, because judges and prosecutors were unaware of parole board procedures and because of inefficient administration and lack of cooperation between law enforcement agencies.

"If you want to know the truth," said one official in D.C. Superior Court, "there wasn't a judge around here who understood what the parole board was doing."

"I gather that the prosecutors were not advising the courts as to what the policy of the parole board was," said Superior Court Associate Judge Fred B. Ugast.

"If you want to know the truth," added a parole board source, "there weren't many prosecutors who knew how it worked either," an assessment that several prosecutors in the U.S. attorney's office who were interviewed did not dispute.

In practice, authorities said, it seemed the only ones who knew how to work the system were defense lawyers, many of whom would use lengthy backup time as an argument for reduced sentences in criminal cases involving parolees.

Judges granted the reduced sentences, apparently unaware that backup time was seldom imposed.

In order for backup time to be effective when a parolee is involved in a new crime, moreover, the parole board must revoke parole before sentencing for the new crime takes place. In most instances, that was not being done, and as a result the backup time and the new sentence were being served concurrently.

According to court sources, judges and prosecutors alike were shocked to learn in March last year that the backup time they had presumed was keeping repeat offenders behind bars was, in fact, virtually meaningless.

Said Ugast: "The judges assumed that the parole board could determine how much time a parolee would have to serve," whether or not parole was revoked before sentencing.

Last year, several meetings were held by judges, parole officials and the U.S. attorney to discuss backup time. Authorities said the situation since has improved dramatically with more efficient use of computer facilities and more aggressive efforts to coordinate activities among court officials, prosecutors and the parole board.

Now, lawyers in the U.S. attorney's office have been directed to attempt to ensure that parole violation warrants are executed before sentencing. In those instances where parole warrants have not been executed, judges now compensate by setting longer sentences in cases involving parolees, assuming the sentences will run concurrently with any penalties the parole board later decides to impose.

The net effect of the new regulations is expected to be an estimated 100 to 200 additional inmates at Lorton prison, where the central facility, which holds about half the 2,500 inmates at the complex, already is 140 over capacity.