The lawsuit that touched off one of Boston's most controversial political battles in the last 20 years originated as a pro bono case accepted by a corporate law firm.

Attorneys at Foley, Hoag and Eliot, a large Boston firm, took on the landmark school desegregation case that has dominated the Boston political agenda since 1974. And they took it free of charge, says one of the firm's lawyers, because they were concerned about the "impact on the community where that discrimination took place."

Now, attorneys for that firm and others wonder why new law school graduates don't show that kind of commitment.

The interest in legal service at the nation's law school still seems as strong as it was 15 years ago. At Harvard, for instance, 90 percent of second and third-year students spend time in school working in clinical and legal services programs.

These days, however, many lawyers and educators say that kind of public interest spirit does not translate into more legal service work after graduation, as it did a decade ago.

They disagree on the explanation. Some cite the complacent "yuppie" mentality of the '80s. Others blame corporations and big law firms for a lack of real philanthropy.

But they reach the same conclusion. Experts say 80 percent of the nation's current legal needs go unfulfilled, and they say the corporate lawyers fresh out of law school are not doing enough to meet that demand.

Ironically, prospective lawyers across the country are still showing interest in public service, at least while they are at law school, most observers agree. The diversity of clinical projects grow every year, with participation generally remaining high.

At Harvard Law School, for instance, the students feel as strongly committed as ever to public service within their educational confines, at least if recent events are any indicator.

After Dean Robert C. Clark decided to close the school's office for public interest career counseling this summer, about two-thirds of the student body signed a petition protesting the decision and reaffirming their support for public service law.

In recent years, Harvard has pioneered many programs which offer affordable legal aid to indigent clients and give students practical experience in the courtroom. The school's Low Income Protection Plan, which guarantees financial support to graduates entering low-paying jobs, has been mimicked at many other leading institutions.

Only about 6 percent of Law School graduates actually pursue full-time public interest careers. But Harvard's staffers say the success of clinical programs should also be measured by how they influence the 69 percent of graduates who enter private firms, where they can do substantial pro bono work.

Pro bono--literally "for good" in Latin--means everything from obtaining restraining orders for battered women to helping the elderly file Medicare appeals, to cases of housing and employment discrimination.

And that is the kind of work law students often perform in clinical projects.

"The experiences derived from clinical work have an strong impact on lawyers--and consequently on the firms they join--whether or not they enter public service jobs or do pro bono work on the side," says Daniel L. Greenberg, director of Harvard's clinical programs. "They can have an important effect on a firm's pro bono commitment."