PARENTS OF MALE teen-age drivers might want to give serious consideration to moving to Pennsylvania. The highest court of that state has ruled that insurers can no longer charge young men more for auto insurance than they charge young women. Such discrimination is in violation of the state's constitution which, like 15 other state charters, has an equal rights amendment.

It happens in the case of auto insurance that eliminating gender as a rating factor may raise rates for young women who now pay lower premiums. But in other lines of insurance -- pensions, for example, and some kinds of health and disability protection -- women must pay more than men for the same coverage. Insurers say there are hard actuarial data to justify sex-based rates: young women have fewer auto accidents, females file more health and disability claims and, because they live longer, they collect pensions for a longer period of time. Women's groups believe it is discriminatory to lump all members of one sex together and would prefer to base rates on other factors -- mileage driven, for example, or smoking habits in the case of life and health policies.

Efforts have been made to eliminate sex-based rating in insurance, but proponents have not had much success in the legislatures. The courts are another matter, though, and that's where the action is now. Last year, the Supreme Court held that employment-related benefits, such as pension and employer-paid health insurance, had to be provided on an equal basis to male and female workers. The recent Pennsylvania ruling on auto insurance will undoubtedly become the basis for similar suits in other ERA states and will be cited in litigation challenging sex-based rates in life and health policies that are not related to employment. Here in the District, the National Organization for Women has filed suit against insurers on the basis of the city's public accommodations law -- a novel approach that surely will be widely followed if the suit is successful.

Restructuring insurance rate-making practices is not a simple or quickly achieved goal, especially when rate differentials may be justified by the actuary tables but nevertheless socially unacceptable. The industry decided years ago not to use race as a rating factor even though white Americans live longer than blacks. There is a demand for equal treatment of men and women by the industry, and slowly, case by case, the courts are ordering it.