The Supreme Court upheld the right of state workers to get time off to care for children or ailing relatives, rejecting an attempt to scale back a law guaranteeing 12 weeks of family leave.

Tuesday's 6-3 ruling is a departure from the court's line of cases that expand state rights at the expense of federal power or laws passed by Congress. The court majority concluded that Congress was within its rights to mandate that states give their own workers the same benefits that the federal Family and Medical Leave Act grants to private sector employees.

State employees can sue in federal court to enforce their rights under the 1993 law, Chief Justice William H. Rehnquist wrote for himself and Justices Sandra Day O'Connor, David Souter, Ruth Bader Ginsburg and Stephen Breyer. Justice John Paul Stevens also agreed with the outcome of the case.

Congress had ample and persuasive evidence that women state employees, like women in the private sector, suffered in the workplace when work and family commitments clashed, the court concluded.

"By creating an across-the-board, routine employment benefit for all eligible employees, Congress sought to ensure that family care leave would no longer be stigmatized as an inordinate drain on the workplace caused by female employees and that employers could not evade leave obligations simply by hiring men," Rehnquist wrote for the majority.

Justices Antonin Scalia, Anthony M. Kennedy and Clarence Thomas dissented.

By relying on evidence that states governments in general had discriminated against their women employees, the court majority treats the states as a monolith, Scalia wrote.

"Today's opinion does not even attempt to demonstrate that each one of the 50 states ... was in violation," of the Constitution's guarantee of equal treatment, Scalia wrote.

"It treats the states as some sort of collective entity which is guilty or innocent as a body."

In passing the Family and Medical Leave Act, Congress said it was acting in part to stop discrimination against both women and men. Women had suffered discrimination in hiring and promotions because of assumptions they would shoulder most of the care for children or sick family, and men had suffered discrimination because they were presumed not to need time off to perform the same care, Congress reasoned.

The Bush administration defended the law as a practical way to counter long-standing discrimination, both overt and subtle.

The court weighed that rationale against state governments' usual immunity from individuals' federal lawsuits. Congress can override that immunity in limited circumstances, and the state of Nevada argued that the case of William Hibbs was not one of them.

The case began as a straightforward claim that Hibbs deserved time off from his job with the Nevada welfare office to care for his ailing wife.

Hibbs wanted to sue the state to enforce his right to family leave, but Nevada claimed it was immune from Hibbs' lawsuit under the Constitution's guarantee of state sovereignty.

In a series of cases, a narrow 5-4 majority of the high court has ruled that Congress overstepped its authority in passing various civil rights and safety laws.

Taken together, the states' rights cases are considered the hallmark of the court's increasingly conservative bent under Rehnquist. It is noteworthy, then, that Rehnquist departed from that line of cases Tuesday.

The Family and Medical Leave Act applies to all workers except those employed by very small businesses. That included the nearly 5 million people employed by state governments and the many million more who work for private companies.

Protections for private workers are not at issue in the Supreme Court case, but the law's defenders said a ruling for Nevada would have undermined the law nonetheless.

The case is Nevada Department of Human Resources v. Hibbs, 01-1368.