Firms are liable for supervisors' acts of harassment if the behavior results in a "tangible employment action" such as a demotion or firing, or if the harassment is deemed sufficiently pervasive to create a hostile work environment, according to Equal Employment Opportunity Commission guidelines issued yesterday.

The new EEOC guidelines spell out the principles laid down in two major Supreme Court decisions last year that said employers are legally responsible for the sexual misconduct of supervisors, even if they knew nothing about the behavior. The decisions made it clear that workers need not prove that an employer knew or should have known about sexual harassment and failed to stop it in order for the employer to be liable for the conduct.

While the guidelines were prompted by the sexual harassment decisions, they also apply to harassment based on national origin, disability or age -- or harassment in retaliation for complaints filed by employees.

"There have been a lot of questions raised over the exact meaning of the principles the court introduced with these decisions," said Ellen Vargyas, legal counsel for the EEOC.

The EEOC guidelines, which offer the agency's interpretation of the laws and court decisions, come after nearly a decade of sharp increases in the number of sexual and other types of harassment cases filed with the EEOC. Officials at the agency say the number of cases began soaring in 1991, when Anita Hill alleged improper conduct by Supreme Court Justice Clarence Thomas while he headed the EEOC, which enforces federal laws banning workplace discrimination. Also that year, Congress first allowed monetary damages to be paid to harassment victims. In 1998, sexual harassment charges made up 11.4 percent of the 80,000 charges filed with EEOC, officials said.

In the guidelines, the EEOC explains the circumstances under which employers can be held liable for unlawful harassment by supervisors, and the agency lays out steps employers can take to prevent and correct harassment and to shield themselves from legal liability.

They say employers should establish and enforce a policy against harassment and establish complaint procedures. The guidelines also make it clear that employers are not always legally responsible for harassment in the workplace.

For example, in cases when harassment does not result in "tangible job action," an employer is not legally responsible for harassment if it took reasonable care to prevent it. Also, an employer may not be legally liable if an employee does not complain about the harassment. In addition, the guidelines clarify that federal law does not hold employers liable for "simple teasing, offhand comments, or isolated incidents that are not extremely serious."

"This guidance marks another step in [EEOC's] ongoing effort to promote voluntary compliance with the equal opportunity laws," said EEOC Chairwoman Ida L. Castro. "Following the steps set forth in this guidance will help employers and employees safeguard their rights and avoid violations of the law."

The guidelines were applauded by women's groups, which say they were looking forward to having the EEOC expand on last year's Supreme Court rulings.

"It is a very down-to-earth and clear document that gives more detail on what the Supreme Court decisions mean," said Yolanda Wu, a staff lawyer with the National Organization for Women's Legal Defense and Education Fund. "One thing that is made clear is that the burden falls on employers to be proactive about preventing harassment."