THANKS TO THE tireless lobbying of Mothers Against Drunk Drivers and the congressional concern sparked by Rep. Michael Barnes of Maryland, America's tolerance for the most frequently committed violent crime in the country has diminished. Many people are thinking twice about getting behind the wheel after drinking--not so much because of any great new surge of conscience, but because of a new surge of tougher consequences. At the state level, Maryland has been among the leaders in strengthening measures to discourage drunk driving. The question now is how much more legislating, if any, should be done in Annapolis--and the lawmakers are proceeding with caution.

At first glance, it may seem as if the house of delegates' rejection of a number of bills sought by Gov. Hughes is evidence of a weakening state stand. But the mere labeling of a bill as "anti-drunk driving" does not automatically make it a sound measure--and legislators are wise to look twice before leaping onto any bandwagon. Members of the house and state senate have noted privately that they have introduced and even voted for many get- tough measures for publicity purposes, in the expectation that the bills would be killed somewhere else along their legislative way.

So when you read that a house committee has killed 20 drunk-driving bills, it is not necessarily a legislative massacre. One of these measures, for example, would have made it illegal to drive for six hours after having a drink. That may seem a worthy objective, but as a practical law it is of dubious value. Far better--and what the committee seems to have done --is to concentrate not on more radical changes, but on improvements in laws already on the books.

One example is the house committee's action to increase the penalties for homicide by motor vehicle while intoxicated. Under the new proposal, a defendant could receive up to three years in prison and a $2,000 fine--increased from two years and $1,000. The committee also passed three bills that would close loopholes in legislation enacted previously.

To proceed carefully is not to shrug off the importance of cracking down on drunk driving, nor should be it read as signaling the end of legislative improvements. Of all the criminal offenses, drunk driving is one where fear of punishment can--and does seem to--make a difference. Maryland's lawmakers are well aware of this, as is Gov. Hughes, and their cooperation and concern have made an important difference already on Maryland's streets and highways.