It is a touchy subject. For years, Harvard has required its professors--some of the world's most prominent scholars--to retire at 70.

Renowned sociologist David Reisman '31 says he, for one, was ready. But others, including former Watergate special prosecutor and Loeb University Professor Archibald Cox '34, would have liked to stay on longer.

Beginning in 1993, when mandatory retirement for professors becomes illegal, scholars will have a choice. And as that year swiftly approaches, the University is preparing to face the complex issues that will follow.

Especially at Harvard, where the teaching load is light and the community is stimulating, officials say this change may move many scholars to consider remaining in their posts long into their later years.

Such an increase in older faculty could lead to substantial policy changes, some administrators predict--policies which some say would throw the security of tenure into question. For instance, Harvard may institute a plan that asks scholars to review their colleagues, to judge whether they are remaining productive.

If there is no mandatory retirement age, then I think, yes, there will have to be [a review] absolutely," says acting Dean of the Faculty Henry Rosovsky. But, he adds, "it is very unpleasant and difficult to review your colleagues of 20 years."

And John Kenneth Galbraith, Warburg professor of economics emeritus, agrees. "It is a difficult decision," he says--a decision all the more complicated at a University where the phrase "lifetime post" is so highly valued.

Yet Galbraith, who chose to step down at 66, says Harvard has a responsibility to make these judgments. "I don't think tenure should protect the no longer competent professor," he says.

Despite Galbraith's "retirement," the economist still runs a busy schedule. At 82, the former presidential advisor and one-time U.S. ambassador to India, is still sought after for his views on world economy and military history.

"If you live this close to the University, you don't retire," says Galbraith. "My experience is you do the same amount of work for half the pay."

Although many emeriti lead active post-Harvard lives, Galbraith says all should have the right to choose their retirement date, as long as their ability to teach and contribute remains consistent.

And that sentiment is just what Congress ruled in 1986, when former U.S. Rep. Claude D. Pepper (D-Fla.) sponsored a bill that forbids age discrimination in employment practices. At that time, universities were given six years exemption from the new law.

When the law was passed, University officials immediately were concerned that professors who stay on long past the traditional retirement age would potentially occupy spaces for new, younger scholars.

At smaller, less research-oriented schools, Rosovsky says, tougher teaching loads will likely lead professors to continue retirement near 65 or 70. But for the nation's top research universities, Rosovsky adds, the problem will remain.

At Harvard, better working conditions may make professors more inclined to remain. For many here, work is their life, the dean says, and most are very unwilling to give it up.