GONE ARE THE days when politicians could dismiss campaigns for mandatory safety-belt laws as little more than the make-work of busybodies infringing on man's individual right to kill himself in a car. Today the evidence is compelling, and polls everywhere show heavy majorities of voters supporting buckle-up laws. It's not just for safety's sake, either, though the connection between belt use and staying alive is a flat-out fact. Voters are realizing how heavily they pay for the failure of others to buckle up. That is, why more and more states are enacting mandatory seat belt laws and why state legislators in Maryland and Virginia should seize the time and work for passage of laws in this year's sessions.

The most impressive evidence for enactment of safety belt requirements is th statistics being gathered week-in, week-out by coalitions of volunteers. The Maryland Committee for Safety Belt Use, for example, found that as of Jan. 19, there had been 42 fatalities on Maryland highways -- 18 more than last year at the same time. Three of the victims were pedestrians and three were motorcyclists. Of the 36 automotive deaths in which restraints might have helped, 34 of the victims were not wearing belts and two were. Finding: 20 of those 34 victims might still be alive had they worn their safety belts instead of sitting on them.

Talk about infringement of people's rights: consider the cost to everyone of fatalities and serious injuries caused by those who choose not to wear belts. Medical rehabilitation, unemployment and welfare services are big-ticket items. The automobile is the leading cause of death among teen-agers and young adults, and the leading cause of long- term disabilities.

It isn't a matter of draconian sanctions, either. The idea is to help everyone remember to buckle up, and to make it a habit. Most of the laws passed by states and by the District of Columbia apply to people in the front seat. The fines are usually in the $15-to-$30 range, and police can only charge people in cars stopped for other reasons.

Legislators who have acted firmly against drunk driving should sense the same strong concern in the growing public campaigns for safety-belt laws. Polls show large majorities in favor. In Annapolis and Richmond, the time for approval is here.