On a crowded court docket last September, it was just another run-of-the-mill drunk driving trial. But for the six jurors who spent the day in Edgartown district court, it demanded a gut-wrenching decision.

"We were really scared we would come up with the wrong answer," said one juror, a 52-year-old woman. "Our initial reaction was to believe the [police] officers, but as we began to examine everything, there were holes. And we couldn't fill in the holes. We couldn't get beyond the reasonable doubt."

The not guilty verdict they delivered came with a price - the conscience of some jurors. "We were petrified we would pick up the paper," she said, "and find this man had hurt someone."

A not guilty finding in court is just one of the many possible outcomes from drunk driving. In the worst case, the cost is measured in human lives. In the best case, the drunk driver lucks out and makes it home without crashing or getting pulled over by police.

More people appear to be taking the gamble. In a statewide public health survey in 1999, 3.1 per cent of some 6,000 Massachusetts residents polled reported drinking and driving, up from 1.9 per cent in 1997.

On the Vineyard, police have stepped up enforcement, arresting more drunk drivers than ever. Last year's total was 244 arrests, and police have set a pace to beat those numbers in 2001 with 230 arrests at September's end, and three months left in the year.

But besides the handcuffs, what's being done to deal with the problem of drunk driving? The answer starts in the courts and, in most cases, ends in a classroom with a 16-week course called driver alcohol education (DAE).

But for police and prosecutors and the therapists who try teaching drivers to change their habits, the process can be frustrating. That jury trial back in September was one of three drunk driving trials in one week that assistant district attorney Susan Wenzel prosecuted. She lost all three, and she wasn't too surprised.

"We always say it's a coin toss. You never know what a jury's going to do, but on the Island, people say you can't win a jury trial on OUI [operating under the influence] trials," said Ms. Wenzel. "Everyone knows each other."

West Tisbury police chief Beth Toomey agreed that the Vineyard presents unique challenges to prosecutors.

"We have an incestuous jury pool here," she said. "A jury trial is hard to win everywhere, but it's really hard to win on the Vineyard. There's a high tolerance here for drinking. With a jury, it's difficult. Unless there's an injury, they don't understand why we're bothering that person."

Sympathy plays a role. "It was such a sensitive issue," said the juror. "For those of us who ever drink, I feel all of us could have been sitting on either side at any given time."

Fewer than 10 per cent of drunk driving cases on the Island land in front of a jury, according to assistant district attorney Lisa Edmonds. The key element - and reason - is the lack of concrete evidence that the defendant was really intoxicated.

Refusing to take a breathalyzer test is a legal option, but that refusal carries a penalty: an automatic 120-day forfeiture of a driver's license. But by law, jurors cannot be told that a defendant refused the test.

"It's important people realize that we're one of the few states left where refusal to take the breathalyzer is not admissible in court," said Ms. Edmonds.

That omission can leave jurors wondering. "We were frustrated," said the juror from September. "What about blood alcohol levels? We just needed more."

Without scientific evidence, the pressure falls on police officers to perform well on the witness stand, convincing jurors that a defendant's slurred speech or failure to recite the alphabet all the way to Z add up to legal intoxication.

"An officer with a lot of experience can get up and testify," said Chief Toomey, but until just a few years ago, many police on the Island had hardly any experience in trial court.

But trial court is not the only place where a defendant can beat the drunk driving charge. When evidence is weak, the district attorney can opt for a lesser plea of operating to endanger. The prosecutor could also push for alcohol treatment or alcohol education classes, but either way, the finding won't stand as a first offense for drunk driving.

"You follow these cases at all," said Chief Toomey, "and we have some frequent fliers."

The district attorney's office could not provide exact data on conviction rates, but Ms. Edmonds said that in most cases, arrests for drunk driving proceed to a guilty plea.

"In the strong cases, when we have civilian testimony or the breathalyzer, the defendants aren't going to want to roll the dice," said the prosecutor.

Most will submit to the evidence and take their medicine: $1,577 in fines, at least a 45-day license suspension and a 16-week course in driver alcohol education. A failed breathalyzer test adds another 90 days on the loss of license. In the weekly court log, it reads as "continued without finding." If they stay out of trouble for a year, the case is ultimately dismissed, but it's not entirely forgotten.

If you're caught driving drunk again within 10 years, that's a second offense, mandating two weeks of inpatient alcohol treatment on the mainland and another DAE course, this time 26 weeks long. Currently, there are 54 people on the Island enrolled in the course and 10 in the second offender program.

Changing the habits of people who drink and drive is no simple task, according to Mary Ellen McElroy, a counselor who teaches one of the 16-week courses run by Martha's Vineyard Community Services.

"For 99 per cent of them, this is not the first time they were driving under the influence," she said. "Some blame the cops. Others say it's good they were stopped. Those folks are easier to deal with. You don't have to cut through the layers of denial and victimization."

The class meets once a week for two hours. One week, a mother whose son was brain-damaged in a drunk driving accident will share her story with the class. The next week, the discussion might focus on blood-alcohol levels. For habitual, lifelong drinkers, Ms. McElroy said, a few drinks will not make them feel too intoxicated to drive, but they may test well over the legal limit of .08.

For some, there's no convincing them to stop drinking. "If they're addicts or alcoholics, you're asking them to give up the most important relationship in their lives," said Rob Doyle, a substance abuse counselor at Community Services who runs the second offender group.

Harm reduction is one approach, and both counselors will suggest that participants consider the cost savings of taking a taxi home next time they drink too much. "We do a money worksheet," said Ms. McElroy. "It's $30 for a cab ride, but if you don't do that, you could be looking at $1,500 in court costs."

Add in attorney costs - up to $4,000 for a defense lawyer to try your case in front of a jury - and the increase in car insurance premiums, and the price of driving drunk can easily climb into thousands of dollars.

A cab ride is just one preventive tool. It was more than 10 years ago that researchers from the Harvard School of Public Health chose the Vineyard as the pilot site for their national campaign for designated drivers. No one has come back to study the long-term effects of that effort, but a national survey commissioned by Harvard in 1998 found that 53 per cent of adults had either served as a designated driver or been driven home by one.

Closer to home, counselors at Community Services point to the success of the Vineyard chapter of SafeRides, a service operated by high school students who will give a free ride home to teenagers who find themselves in an unsafe situation, such as too intoxicated to drive.

"It's a wonderful sign that kids are getting the message," said Tom Bennett, director of Island Counseling at Community Services.

Still, Pam Carelli, the founder of the SafeRides program here, said the problem of driving under the influence is far from solved. "There seems to be an alarming shift in the thinking of kids," she said. "They accept that alcohol is bad, but they think substances - drugs - are not."

And as teenagers cross the threshhold into their 20s, she said, they are much less likely to be looking for rides. "The older you get, the more likely you are to drive your own self," she said.

Unfortunately, drinking or using drugs impairs not only driving skills but also the good judgment involved in deciding not to drive. "Harm reduction," Mr. Doyle said, "it goes out the window when the person has a couple pops.

"Long term, you have to make it uncool, the way cigarettes became uncool, make it that way with getting behind the wheel."