On May 12, the U.S. Court of Appeals for the 9th Circuit handed down a decision against Microsoft Corp.that could profoundly affect all businesses, especially high-tech companies. Vizcaino v. Microsoft , 173 F.3d 713 (9th Cir. 1999). The court held that Microsoft’s “temporary” employees are entitled to the same benefits accorded full-time employees, including stock options. On May 24, “volunteers” at AOL sued the company to collect back pay and overtime. A Texas court ruled in June that a woman can pursue an employment discrimination suit against a company for which she had never worked.

How does an employer guard against such suits? The answer is to be found in the legal definition of “employee.”