Five years ago, a conviction for drunk driving might have resulted in a fine, a warning or, in rare cases, a suspension or revocation of a driver's license. Those days are gone. Appalled at the havoc caused by those who drink and drive, the public has demanded tougher treatment of offenders, and across the country legislatures and courts have responded. Since 1981, more than 30 states have enacted legislation aimed at this problem; most often these statutes increase penalties for drunk driving and many impose mandatory jail sentences. In some jurisdictions -- Minneapolis is one -- judges have, by consensus, adopted these policies even in the absence of legislation.

Putting the new rules into practice, however, creates difficulties for courts and for corrections institutions. The National Institute of Justice has just released a study on the impact of laws requiring mandatory sentences for drunk driving. Arrests increase when the new sanctions are publicized and so does public concern. These changes produce exactly the right result: traffic fatalities decline. But courts have trouble keeping up with the increased caseload.

A new legal specialty has arisen in this field where, in the past, an attorney was often not necessary. These experts command large fees to defend drivers facing mandatory jail sentences. As a result, cases are more often contested, lengthy and expensive. In Seattle, for example, the law was amended in 1980 to require that all those convicted of drunk driving serve at least one day in jail. Before that, only 9 percent had been incarcerated. Now, three judges have been added to the six who had previously handled these cases. Jury trials have doubled, and the county has had to open a new corrections facility to handle first offenders. runk drivers now represent about 70 percent of the probation-department caseload.

The public is willing to absorb these costs because, in the long run, it is expected that increased penalties will have a deterrent effect. The NIJ study is a useful document for legislators and judges who, by careful planning, might be able to avoid some of the problems that arose in pioneer jurisdictions. Weekend sentences, for example, were thought to be a useful procedure for dealing with offenders who could continue to work and support families. In large numbers, though, they are tremendously disruptive to the prison system. Special provisions must be made for those with no prior criminal record, and treatment programs must be coordinated with penalties. Planning is important if these new laws, enacted with such widespread public support, are to be effective.