THROUGHOUT the abortion debate in the Maryland legislature last spring, both sides repeatedly called on Gov. William Donald Schaefer to take sides and assume a leadership role. He declined to do so. Now, after conferring with religious leaders and political colleagues, after reading thousands of letters from Marylanders on the subject and after reviewing the stunning election returns in primaries earlier this month, the governor has announced his position. It is a decision that will surely please the abortion rights groups that made such a strong showing in the primaries.

Gov. Schaefer claims that his personal opposition to abortion is as strong as ever. But in his official capacity he has pledged to veto any legislation that would impair a woman's own right to choose an abortion in the early months of pregnancy. While he refused to extend this promise to proposals involving parental consent or third-trimester abortions, his stated position greatly strengthens the hand of those who want to lock in rights now protected by the courts.

Maryland is one state that has not sought to chip away at abortion rights. There are no parental notification requirements, no restrictions on public hospitals or public health employees, and the state even pays for some Medicaid abortions. The attorney general of the state has ruled, however, that if Roe v. Wade were to be reversed, an old 1968 law -- never repealed, but unenforced since 1973 -- would be revived. That law allowed abortions only in cases of rape, fetal abnormality or when the life of the mother was at stake. Abortion rights legislators tried last March to repeal this old law so that there would be no restrictions on the right should Roe be reversed; the effort ended in deadlock. Changes in the legislature and the governor's promise not to oppose such an effort give new impetus to reform.

It is remarkable that Gov. Schaefer was able to avoid taking a position on abortion for so long. His belated decision was the right one.