When Dan Leach was named to the Equal Employment Opportunity Commission five years ago, the agency had 150 pending cases in which people claimed they were vampires and were suffering discrimination because they were born in Transylvania.

"No kidding. I'm serious," said Leach in an interview at the law firm he recently joined after stepping down as commission vice chairman. Some of the staff who handled these charges, he recalled angrily, were so mindless and overzealous that instead of immediately tossing the charges out, they let them get as far as preliminary examinations.

"We threw that out and stopped that kind of frivolous waste of time," said Leach.

But he said it is a good example of the willingness to believe any charge that characterized some of the early "hair shirt" affirmative action enforcement efforts by a number of federal, state and local agencies.

Leach said that in the early days of affirmative action, there were too many automatic findings of discrimination regardless of the facts of a particular case, too many field agents who refused to accept justified employer tests of skill or competence, too much mindless quota-setting and insistence that the proportion of blacks on a company's employment rolls match the total number of blacks in the local labor force, regardless of how many of them actually had the skills needed to do the job.

These things weren't the rule, argued Leach, who was counsel to the Senate Democratic Policy Committee for 10 years before President Ford appointed him to the EEOC. But they were common enough to damage the concept of affirmative action and lead to the reaction against it now taking place.

And that is a shame, Leach said, because properly applied and administered, the principles of affirmative action are actually no great burden for any company to comply with.

The basic rule is rather simple, said Leach. The number of minority members in any company's work force should be roughly proportional to the number of minority persons in the overall local labor force who have the requisite skills genuinely needed for the job.

If only a tiny number of blacks in an area have the skills, then the employer can't be expected to have a huge number working for him. But if the employer is using some exaggerated skill requirement or test, far in excess of what is really needed for the job, then the law can force him to drop it and use a more reasonable one and to set goals for hiring more qualified minority members.

Leach said that agencies and courts are focusing more and more on the question of whether there are qualified minority workers. Employers will not be punished for having few minority employes if they can show that the skills and qualities they demand are, in fact, reasonably relevant to the job, and that the minority labor pool with those skills is very small.

Of course, he said, the skills really have to be job-related. "If you're asking people to turn widgets, are you demanding a college degree? There was a company in Oklahoma, and for hiring truck drivers, it was requiring them to read Shakespeare aloud, to prove they could read highway signs. Is that reasonable?"

On the other hand, he said, if you were looking for nuclear physicists, you couldn't just use the proportion of blacks in the labor force to decide whether your company's work force has a reasonable proportion of blacks. The base you'd use would be the proportion of black nuclear physicists in the local labor force.

Leach concedes that in practice this simple theory can turn up problems. Overzealous enforcers anxious to build up minority employment rapidly can simply refuse to concede that virtually any skill or qualification is really necessary to be able to perform the jobs in question.

But he says that even the much-criticized EEOC found 75 percent of the tests submitted for review were valid even though they had an adverse impact on minority hiring.

For managers of businesses, for example, it found various types of problem-solving and crisis-meeting simulations valid. It found personality tests and "traits" tests valid for hiring of law officers and salesmen, math tests relevant and fair for jobs clearly requiring such skills.

"Don't get me wrong, I'm no zealot and I know what the abuses have been," said Leach. "But properly understood and carried out, affirmative action is reasonable and defensible."

As for the vampires, before throwing their complaints off the docket, Leach recalls, he told the staffers that instead of processing them, maybe they should "buy 150 stakes and drive them through their hearts."