“In sum, Congress’s power to legislate with respect to Indians is well established and broad,” Justice Amy Coney Barrett wrote. “Our cases leave little doubt that Congress’s power in this field is muscular, superseding both tribal and state authority.”

Barrett wrote that the couple and the states were trying to create a “constitutional carveout” that family law is wholly exempt from federal regulation while it is not.

The case, Haaland vs. Brackeen, was brought by Chad and Jennifer Brackeen, a White Texas evangelical couple who wanted to adopt a Native American boy and argued that the preference granted to Native Americans in adoption constituted racial discrimination in violation of the 14th Amendment.

The couple attempted to adopt a 10-month-old referred to in the court decision as A.L.M. The child’s mother is a member of the Navajo Nation and his biological father is a member of the Cherokee Nation, according to court documents.

The tribes opposed the adoption while the child’s mother, father and grandmother supported the adoption. The Navajo Nation designated A.L.M. as a member and informed a Texas court it had found a tribal adoptive family in New Mexico.

The Brackeens sued to block the tribe’s action and the Navajo family withdrew from the adoption. The couple sought to adopt a second child, A.L.M.’s biological sister identified as Y.R.J., who lives with the family. The Navajo Nation objected again.

Justice Brett Kavanaugh wrote that the racial discrimination issue was not settled by the decision and represented a “serious” question the court should return to in a future case.

Matthew McGill, a lawyer representing the Brackeens, said he would pursue the racial discrimination claim in state court.

“Our main concern today is what today’s decision means for the little girl, Y.R.J. — now five years old — who has been part of the Brackeen family for nearly her whole life,” said McGill.

The states of Texas, Indiana and Louisiana joined the case on the side of the couple seeking to overturn congressional authority to give adoption preferences in these cases to Native Americans and tribal governments, contending among other things that the federal government could not trump the power of state courts in Native American children adoption cases.

But the majority decision said the court “specifically recognized Congress’s power to displace the jurisdiction of state courts in adoption proceedings involving Indian children.”

The Supreme Court also found that Texas, which led the state effort to overturn the Appeals Court ruling in the case, lacked standing because it would not be injured by the adoption placement preferences in the ICWA.

Justices Clarence Thomas and Samuel Alito dissented as Thomas wrote the majority established “only that Texas has failed to demonstrate that ICWA is unconstitutional” and Alito argued Congress’ power over Indian affairs is plenary and not absolute.

The ICWA giving Native Americans preference in these adoptions was passed after a long history of Native American children being disproportionately removed from families by state and federal governments. Tribes oppose that practice, believing that the ICWA preference for Native Americans in these adoptions helps preserve tribal culture.

President Joe Biden said in a statement praising the ruling that the nation’s “painful history looms large over today’s decision.”

“Tribal Nations fought hard to pass the Indian Child Welfare Act and I am proud to have joined them in the ongoing efforts to defend it,” Biden said. “Vice President [Kamla] Harris and I will continue to sand with tribes to protect Native children, honor tribal sovereignty and safeguard the essential principles of the Indian Child Welfare Act.”