NEW ORLEANS — A federal appeals court announced Thursday that it will take a second look at an emotionally fraught lawsuit governing the adoption of Native American children.

In August, a three-judge panel of the 5th U.S. Circuit Court of Appeals upheld the Indian Child Welfare Act of 1978. It was a defeat for non-Indian families in multiple states who had adopted or sought to adopt American Indian children.

On Thursday, the New Orleans-based court said a majority of its active judges have voted to re-hear the case. It means Native American tribes and the federal government will again have to defend the law, which they say is critical to protect and preserve Native American culture and families.

A hearing date has not been set.

The lead plaintiffs in the lawsuit challenging the law are Chad and Jennifer Brackeen, a Texas couple who fostered a baby eligible for membership in both the Navajo and Cherokee tribes. The boy’s parents voluntarily terminated their parental rights and the Brackeens petitioned to adopt him. After legal battles, they were able to keep him when a placement with a Navajo family fell through. They hope to adopt his younger half-sister, according to briefs.

Other plaintiffs include Jason and Danielle Clifford of Minnesota, who were unable to adopt a child who lived with them after having been shuttled among foster homes. “The Cliffords’ family was literally torn apart,” their attorney told the appeals court judges during arguments in March.

Texas, Indiana and Louisiana have also joined the lawsuit, siding with the would-be adoptive families.

Defendants include the federal government and numerous intervening Native American organizations and tribes who back the law. They say that without it, many Native American children will be lost to their families and tribes.

“Tribal nations are still reeling from generations of our families being separated,” Tyson Johnston, vice president of the Quinault Indian Nation said in March after a 5th Circuit hearing. “So, even though we’ve had good policy like the Indian Child Welfare Act, it’s going to take us many more generations to rectify those past wrongs.”

Opponents of the law called it an unconstitutional race-based intrusion on states’ powers to govern adoptions. But two members of the three-judge panel that ruled this year disagreed.

The opinion written by Judge James L. Dennis said the law’s definition of an “Indian child” is a political classification. It said the definition is broad, “extending to children without Indian blood.

, such as the descendants of former slaves of tribes who became members after they were freed, or the descendants of adopted white persons,” Dennis wrote.