Despite a patchwork of federal, state, and local laws designed to protect caregivers from being fired, demoted, or otherwise penalized at work, plenty of employees find that taking unpaid time off — or even asking for other kinds of flexibility — is still risky. So, according to a new analysis by the Center for WorkLife Law at the University of California’s Hastings law school, many more of them are suing. Record numbers are winning, too.

Between 1998 and 2012, federal employment discrimination cases declined overall. But not employee lawsuits over family-leave discrimination: They shot up 590%. In the past 10 years, although the largest category of claims (67%) was about pregnancy discrimination, the fastest-growing type — up 650% — was brought by employees who were taking care of elderly relatives. Nor is this a “women’s issue.” Well over a third (39%) of those eldercare actions were brought by men, who also filed 336% more paternity-leave lawsuits than in the decade before.

For employers, this gets expensive. Plaintiffs have been winning cases about 70% of the time, the study says, or more than twice as often as they prevail in other kinds of employment suits. Altogether, litigation over what the study calls “FRD,” for family responsibilities discrimination, has cost employers almost half a billion dollars ($477,009,417) between 2006 and 2015, more than double what it cost in the previous decade. And that’s a conservative estimate, because it doesn’t include the cost of confidential out-of-court settlements.

“Some employers still aren’t getting it when it comes to discriminating against employees with family responsibilities,” notes Joan C. Williams, director of Hastings’ Center for WorkLife Law. In the belief that better training for front-line supervisors would help, the center offers free resources, including a webinar for managers, on its Pregnant@Work web site.

Part of the solution, says Cynthia Calvert, who led the study, might be “a work coverage plan,” meaning a blueprint for how every employee’s work would get done if he or she were absent for any reason. “If you plan for the possibility that anyone could be gone for an extended period — his or her own health, travel, family — then leave becomes normal and not a sign that the employee is not committed,” says Calvert.

A work coverage plan also “forces supervisors to recognize a fundamental truth,” Calvert adds. “Almost every employee will be a caregiver at some point in his or her career.”