THE TOUGHEST PART of fashioning affirmative action programs is balancing the ideal of selection without discrimination with the need to allow historically underprivileged minorities to catch up to more advantaged groups. At the Law School, the Harvard Law Review recently struck this delicate balance so it could select more minority students for the staff.

Now the Law School in again debating affirmative action, but this time the discussion goes beyond the Law Review staff. The newest affirmative action proposal before the law school would mandate heightened searches for Law faculty, among other things. That body currently boasts just one tenured Black among its 64 tenured professors, and officials foresee no dramatic jump in that figure in the near future.

The plan offered last week by the Third World Coalition, a coalition of minority student groups seems worthy of serious consideration. Not only is it aimed at redressing an imbalance that may limit the perspectives offered by law professors, but its emphasis on paying special attention to minorities avoids the pitfalls of using reverse discrimination to counteract past injustices.

Instead, the plan would require the Law School to scrutinize especially carefully the qualifications of possible faculty members who are minorities. The school would also be expected to hire two visiting minority professors each year and establish a committee to search for minority faculty. The Law School would consider the committee's nominees for vacant tenured positions.

The plan would give minorities increased opportunities to fill spots that have been closed to them in the past instead of filling positions with minorities through quotas or lowered standards. The Law Faculty for too long has been too homogeneous to provide diverse perspectives to tomorrow's lawyers. The coalition's proposal just might help rectify that problem without forcing the school to compromise its standards.