MORE THAN 12,000 PEOPLE are likely to get acquired immune deficiency syndrome (AIDS) in the next year, according to the Centers for Disease Control. For employers, that could mean 12,000 legal problems.

Lawyers are suddenly very busy fielding calls from employers who are trying to guess how courts and administrative agencies will rule in a growing number of AIDS-related suits. "Three months ago, I never got a call on AIDS," reports Gregory Rasin, a lawyer who specializes in employment law. "Now I get calls every day from employers."

The angriest disputes involve charges of employment discrimination. The first case to reach trial may be that of Todd Shuttleworth, a former analyst for a county budget office in Florida. Fired after he got AIDS, Shuttleworth is suing for $15 million. "Employees with AIDS are being denied the dignity of having a job and the income that comes with a job," says Allan H. Terl, who heads a Florida chapter of the American Civil Liberties Union. "Cases like this are popping up all over the country." A major question is whether people with AIDS are protected by laws that prohibit discrimination against disabled workers.

Judges will hear some unusual cases involving confidentiality, too. In Massachusetts, an employee who suffers from AIDS-related complex is suing his employer for breach of confidentiality and for inflicting emotional distress. A rumor was spread after he privately told his supervisor that he was having an AIDS test.

Then there are fearful co-workers, who may sue if their employer doesn't fire an employee with AIDS. Sensitive questions about how far a company must go to protect its healthy workers will probably reach the courts. "We get lots of phone calls from co-workers who say, 'I don't want to have to sit next to a man with AIDS," says Thomas Stoddard, legislative director of the New York Civil Liberties Union. "We're going to see a higher number of legal cases quickly."