FEDERAL JUDGES, as a general rule, shouldn't sling college professors into jail for refusing to testify about promotions. In particular, they shouldn't jail professors in matters of conscience, especially where the testimony is not necessary to the case being tried. Judge Wilbur Owens went much too far in sending James Dinnann of the University of Georgia to prison for 90 days. Although Professor Dinnann has been released, an appellate decision might conceivably return him there.

But if the judge's reaction was excessive, the witness was defending a dubious principle. Professor Dinnann evidently believes that the academic committees that hire, fire and promote are not ever to be held under any circumstances accountable to any other authority. That comes uncomfortably close to a declaration of immunity from the federal laws against discrimination.

There's been a good deal of discrimination in academic life in the past, and the courts are necessarily the wronged teacher's last resort.But courts are not well adapted to referee questions of promotion. The assessment of the quality of teaching is always to some degree subjective, and to know the worth of scholarship requires deep specialization. If ever there were an area in which the courts needed to show a special restraint, it is this one. The standard for intervention in academic tenure cases ought to be a showing of illegal discrimination that is unarguable and overwhelming.

In the decisions over tenure, it's the top jobs that are at stake -- and not only jobs, but jobs for life. They carry high rank in this country, and usually confer substantial influence.

Unhappily for teachers not yet tenured, the rules of the game have changed drastically in the past decade. That acounts for some of the passion in these suits. In the 1950s and especially the 1960s, when the whole higher education system was expanding rapidy, anyone with a doctorate and patience could expect tenure eventually. Today the graduate schools are churning out large numbers of highly qualified scholars, but -- because of the turn in the birth rates 20 years ago -- the numbers of undergraduates, and of tenured faculty to teach them, will inevitably decline. Promotions that were once a matter of course and almost of right can now be awarded only in cases of exceptional distinction. As the competition for tenure increases, there will be a rising temptation for the losers to go to court charging discrimination. The judges need to make it clear that they will intervene only where violations are compellingly clear.