In a decision that will be welcomed by Americans struggling to pay for home care, the U.S. Supreme Court ruled yesterday that home care attendants hired through an agency are not covered by the federal minimum wage and overtime benefits.

In so ruling, the federal high court rejected a suit brought by a retired home attendant from Queens, Evelyn Coke. Ms. Coke, 73, had sued her former employer, Long Island Care at Home Ltd., for back pay.

A federal appellate court had previously sided with Ms. Coke. The unanimous decision, written by Justice Breyer overturns the Second Circuit Court of Appeals, which sits in Manhattan.

Justice Breyer upheld Department of Labor exemptions of such workers from federal overtime pay and minimum wage regulations. The exemptions were part of an “Interpretation” of a 1974 amendment to the Fair Labor Standards Act. The ruling applies only to home care attendants who are hired through an agency.

New York City had weighed in on the issue in a brief to the court, saying that its share of Medicaid costs would go up if home care attendants were better paid. The city estimated that it would need to raise its annual Medicaid payments to $1.871 billion, an increase of about $279 million, if the high court sided with Ms. Coke.

“The ruling properly deferred to the agency’s exercise of authority expressly delegated by Congress to fill gaps in the legislation,” a city lawyer, Susan Choi-Hausman, said in a statement responding to the ruling.

In its brief, the city has also questioned whether overtime pay would result in higher compensation for home care attendants. While some attendants currently work shifts as long as 24 hours, the city suggested that, were agencies ordered to pay overtime, they might simply introduce more shifts. Increasing the number of attendants who cycle through a home could result in a drop in the comfort level that a client has with an attendant, the city’s brief argued.