WASHINGTON — The nation's growing cadre of home healthcare aides is not entitled to minimum wages or overtime pay under federal law, even if they work for private employers, the Supreme Court ruled yesterday.

The 9-0 decision, which keeps in place a long-standing rule that denies minimum wages and overtime pay to those who provide "companionship services" at home, could trigger a move in Congress to amend the law.

With an estimated 1 million workers assisting the elderly and the disabled in their homes, unions and civil-rights groups had urged the justices to scrap this rule because they say it deprives many of the nation's lowest-paid workers of a living wage. They said a large percentage of these aides are women and minorities who often work all-night shifts. Yet, under federal labor law, they are viewed the same as part-time baby sitters.

A U.S. appeals court in New York had ruled that the minimum-wage law applied to those home-care workers who are employed by a private company or a public agency. If it had been upheld, this decision would have given overtime pay and minimum wages to the vast majority of the nation's home-care workers, since most are employees of companies.

But the Supreme Court said, in essence, it is up to Congress or the Labor Department to change the Fair Labor Standards Act. Passed by Congress in 1938, the law is enforced through rules issued by the Labor Department.

The decision is "another blow to struggling, low-wage women," said Nancy Duff Campbell, co-president of the National Women's Law Center.