WASHINGTON — The Supreme Court on Thursday handed a major win to Native Americans by rejecting a challenge to a federal law aimed at protecting children and buttressing tribal identity.

In a 7-2 vote, the court turned away a series of claims seeking to invalidate parts of the Indian Child Welfare Act enacted in 1978 to keep Native American children within tribes. Among the provisions challenged was one that gives preference to Native Americans seeking to foster or adopt Native American children.

The court, in a ruling authored by Justice Amy Coney Barrett, said the challengers did not have legal standing to contest whether the preference provisions violated the equal protection clause of the 14th Amendment by discriminating on the basis of race.

Barrett wrote that the challengers had sued the federal government, but noted that it is state courts that enforce the preference provisions and that state agencies place the children. Therefore their claims could not be redressed by the federal government and must be dismissed, she said.

The majority did, however, conclude that Congress has the authority to legislate on the issue of Native American family law and rejected challenges on those grounds.

Barrett wrote that the challengers were seeking a “constitutional carveout” saying Congress cannot legislate on family law, but that since the founding of the United States, it has been clear that Congress has broad authority to pass laws on a wide range of issues.

“Family law is no exception,” she said.

The ruling will come as a major relief to tribes, who were concerned that the court would weaken or entirely strike down a law that plays an important role in maintaining tribal identity.

“By ruling on the side of children’s health and safety, the U.S. constitution, and centuries of precedent, the justices have landed on the right side of history,” the leaders of four tribes involved in the case, Cherokee Nation, Morongo Band of Mission Indians, Oneida Nation, and Quinault Indian Nation, said in a joint statement. Another tribe, Navajo Nation, also defended the law.

“With these latest political attacks on ICWA now behind us, we hope we can move forward on focusing on what is best for our children,” the tribal leaders added.

The ruling also marks the second time this month that the court has rejected conservative efforts to rein in laws aimed at protecting minority groups, following the ruling last week to reaffirm a key part of the Voting Rights Act. The court has yet to rule on another big race-related case in which it could end the consideration of race in college admissions.

Two of the court’s six conservative justices, Clarence Thomas and Samuel Alito, dissented.

Alito wrote that although Barrett said the law concerned vulnerable children, the ruling “disserves the rights and interests of these children and their parents, as well as our Constitution’s division of federal and state authority.”

The law was enacted in response to a long history of Native American children being disproportionately removed from their families by both states and the federal government.

The challengers are led by Chad and Jennifer Brackeen — a white evangelical Christian couple who sought to adopt a Native American boy — as well as the states of Texas, Indiana and Louisiana. The couple adopted the child after a potential placement with a Navajo family fell through. They are also seeking to adopt the child’s half-sister, who lives with them.

The law was defended by the Biden administration and the five tribes,

The tribes warned that striking down provisions of the law on racial discrimination grounds would threaten centuries of law that treat Native American tribes as distinct entities.

Both sides appealed to the Supreme Court after the New Orleans-based 5th U.S. Circuit Court of Appeals in 2021 issued a splintered decision in which judges were divided over the key issues. A district judge had previously held that the law was unconstitutional.

The Supreme Court has been closely divided in two major recent cases on Native American issues. In 2020, the court expanded tribal authority in Oklahoma in a 5-4 ruling authored by Justice Neil Gorsuch. But in a follow-up case last year seeking to limit the impact of the earlier ruling, the court reversed course, ruling 5-4 to widen state power over tribes in certain instances.

Between the two rulings, liberal Justice Ruth Bader Ginsburg, who had sided with the tribes in the 2020 case, died and was replaced by Barrett, creating the court’s current 6-3 conservative majority. Barrett cast the deciding vote against the tribes in the second case, while Gorsuch joined the three liberal justices in dissent.