In a letter to U.S. Labor Secretary Elaine Chao, 200 state and national groups - representing women, minorities, labor and senior citizens - said the proposed changes would "roll back" the protections provided by the 12-year-old act by denying millions of American workers the ability to take time off for their own illness or that of a family member. 

The law allows workers to take as much as 12 weeks of unpaid leave per year for the birth or adoption of a child, or for their own illness or that of a family member, while protecting their jobs. 

The groups fear that changes sought by business groups would restrict the kinds of medical conditions covered by the law as well as force employees to take "intermittent leave" for such concerns as chemotherapy in larger chunks of time than they need, using up their allotted annual leave too quickly. 

Such changes "would have a devastating impact on American families," Debra L. Ness, president of the National Partnership for Women & Families, said at a news conference yesterday. "They would make it harder for people to take advantage of the law and to use the protection of the law." 

Linda Meric, head of the national group known as 9to5 that champions economic justice for women, said: "At the same time that big-business groups are attempting to lessen workers' access to [the law's provisions], the greatest problem we've seen is that millions of workers aren't covered by it," because companies governed by the law must have 50 or more employees. 

Department of Labor statistics show that about 60 percent of workers are covered by the act, known by the acronym FMLA. 

But business groups, including the U.S. Chamber of Commerce and the National Association of Manufacturers, say it's clear that some changes are needed in the law's provisions to help employers deal with workers who use its job protection as cover for their chronic tardiness or absenteeism. 

Particularly problematic are what business groups consider the act's overly vague definition of a "serious medical condition" as well as a provision involving "intermittent leave," which business officials said can amount to just 10 minutes in some instances. 

"We've now got 10 years of experience with these regulations," said Michael Eastman, the chamber's director of labor law policy. "There are a few parts of them that have made it very difficult for employers to combat the minority of employees - but a significant minority - who are abusing the law." 

Because of a 2002 U.S. Supreme Court decision, the Labor Department must change one part of the FMLA dealing with the notice that employers must give workers about how they are implementing the law. It is uncertain when the department will respond to the Supreme Court ruling, and whether it will also use the opportunity to deal with other issues affecting the act. 

"No final decisions have been made," said Victoria Lipnic, assistant U.S. labor secretary for employment standards. 

More than 50 million Americans have taken job-protected leave under the FMLA since 1993, according to a Labor Department survey in 2002, the most recent statistics available. The majority of those people - 52 percent - used the leave because of their own serious illness, while 31 percent used it to care for a seriously ill family member. The rest used the leave to care for a new child. 

Of those who used the leave for illness, half were off work for 10 days or fewer, according to the department survey. More women (58 percent) than men (42 percent) have used the FMLA.