FAIRFAX COUNTY Commonwealth's Attorney Robert F. Horan has complained vigorously about the early releases from prison of two teenagers convicted of arson in the burning of Vort Hunt High School and of a convicted bingo operation whose illegal operations earned more than $1 million. The youths were freed after serving three-and-a-half months of their one-year sentences. The bingo operator, sentenced to four years, spent two months in jail before being released in a program that allows him to work by day and spend his nights in jail. Mr. Horan says it's a miscarriage of justice for the three to have been freed so quickly, and he condemns the Virginia General Assembly's recent changes in sentencing procedures, under which these releases came.

Mr. Horan's concern is understandable. Both the prosecutor and society at large are entitled to expect some certainty about what the sentences set by judges or juries will actually turn out to be. Moreover, the state parole board may have mistakenly counted time spent in jail before conviction in applying the new law to the two arsonists. Still, these three cases do not justify the broad attack Mr. Horan has made on the law.

The purpose of the new procedures is to smooth the transition from prison to outside life. A sponsor, Del. Frank M. Slayton (D-Halifax), notes that cutting prison terms by six months and placing convicts under close supervision for the remaining period is "a positive step in attempts to rehabilitate convicted criminals." There will be always be exceptions, but this trend toward better "mainstreaming" of inmates, coupled with requirements for community service or other forms of restitution, makes more sense than jam-packing prisons and then releasing prisoners to the streets cold.

In the cases cited by Mr. Horan, incarceration is not all that is involved. The two youths were ordered to complete 3,000 hours of volunteer community and to pay $10,000 in restitution for their role in the arson; and the bingo operator is paying for his room and board in jail while earning a living.

Rather than backing away from the new sentencing laws, as Mr. Horan has suggested, Virginia should focus on the more delicate question of how to balance the proper role of judges and juries in sentencing, with the constructive exercise of discretion by prison officials in phasing their charges gradually and safely back into society.