WASHINGTON - The Supreme Court divided along ideological lines Tuesday in ruling that states may not be sued by their employees for illegally denying them medical leave.

States are generally immune from lawsuits seeking monetary damages, and the court's conservative majority said in a 5-4 decision that the restriction should apply when the issue at stake is the sick-leave provisions in the federal Family and Medical Leave Act.

The court ruled differently on another portion of the law in 2003. It said that violating its family-leave provisions could open a state to lawsuits.

Justice Anthony Kennedy, who wrote Tuesday's decision, said that is because Congress had found evidence that states "had family-leave policies that differentiated on the basis of sex and that states administered even neutral family-leave policies in ways that discriminated on the basis of sex."

But Kennedy said Congress had not found evidence of discrimination or sex stereotyping when it came to sick leave. Justice Ruth Bader Ginsburg summarized the dissent of the court's liberals from the bench, an act reserved for disagreements of special consequence.