The Virginia General Assembly, reacting to a statewide outcry over highway fatalities, today gave final approval to legislation that would stiffen the state's drunken driving laws, capping one of the more emotional debates of the 1982 session.

The measure provides for mandatory jail sentences for repeat offenders -- a minimum 48 hours in jail for a second offense, and a month in jail and lifetime license revocation for a third -- and wipes out an existing provision in state law that has allowed persons to avoid drunk driving convictions by completing a state-run alcohol education program.

The final product was described today as a compromise between a Senate bill derided by detractors as "draconian" and a milder House version.

"This is going to have an impact on our highways because it's got mandatory jail and that's what people understand," said Sen. A. Joe Canada (R-Virginia Beach), a sponsor of the measure. "No matter how rich or poor you are, you're still going to have to go to jail under this bill."

Canada allowed, however, that the bill was still a far cry from the measure that had been backed by a citizens' group called Mothers Against Drunk Drivers (MADD) and had passed the Senate last month. That bill, which called for mandatory jail terms for the first drunken driving conviction, had been jettisoned by the defense lawyers who dominate the House Courts of Justice Committee.

"It's true that this is not all we had hoped for," said Canada. "But it's a step in the right direction."

Passage of the bill concludes one of the more effective grassroots lobbying campaigns to hit the capital in years. The MADD group organized a network of parents around the state who inundated legislators with phone calls and letters, staged press conferences and showed up at committee hearings to tell heart-wrenching stories of their children and friends killed or injured by drunk drivers. Together with an off-shoot group called SADD (Students Against Drunk Drivers), the group climaxed its campaign with a candlelight vigil on the Capitol grounds.

"We covered every angle we could possibly think of," said Susan Midgett, a Norfolk housewife and MADD's president, whose 14-year-old son was killed two years ago when a drunk driver swerved off a road and struck the youngster on her front lawn. "That's what it took to pass the bill -- the outcry of Virginia citizens."

Canada was one of a number of lawmakers who agreed today that even the compromise bill never would have passed had it not been for the MADD campaign. "That's what did it; that's what passed this bill," he said. "If you talked to House members early on, they said, 'You're crazy, there's no way you'll get a mandatory jail bill.' But we generated as much public interest with this bill as any I've ever seen."

Midgett said that while MADD did not get everything it wanted, the final version "has got the strongest provision that we were trying to get. Now we're going to be monitoring the courts to make sure that the judges and prosecutors use it."

The provision to which Midgett referred -- a central feature of the House bill introduced by Del. Mary Sue Terry (D-Patrick) -- would end the current practice of reducing or dropping charges against first-time drunken driving offenders who complete the state's Alcohol Safety Action Program.

The program, labeled a loophole by critics, has allowed thousands of drivers to escape drunk driving penalties, in some cases as many as three or four times. First-time offenders who decline to enter the program would lose their licenses for 60 days.

Although the House rejected MADD's proposal to impose a mandatory 48-hour jail term or mandatory 90-day suspension of the driver's license for the first offense, it did agree to considerably tougher penalties for repeat offenders.

A major criticism of the state's drunk driving laws is that, while authorized penalties are stiff -- up to six months in jail for the first offense, for example -- they are rarely sought by prosecutors or imposed by judges. Under the compromise bill, judicial discretion would be sharply restricted for repeat offenders.

A person convicted of drunken driving for the second time would receive a sentence of at least 48 hours in jail and a one-year license suspension, with a special permit for commuting to work.

Persons convicted of drunken driving for the third time would receive one month in jail and a lifetime revocation of their licenses.

The bill sailed through both houses today by votes of 37-to-0 in the Senate and 88-to-8 in the House.

Some dissenters suggested the bill, which Gov. Charles S. Robb is expected to sign, won't have nearly the impact that supporters claim. "This does a slight bit more than we have now, but it doesn't address the real problem," said Sen. Dudley J. Emick (D-Botetourt). "I'd say this is next to nothing."