In the biggest U.S. Supreme Court week in years, with banner headlines on race and marriage, the court decided a small case no one much noticed. But in its own way, it reflected societal changes as profound as those captured in the court’s rulings on the Voting Rights Act and Proposition 8.

At stake was nothing less than the question of whether a biological father who doesn’t support his child is really a father at all -- and the court, led by its younger conservative justices, said he wasn’t.

True, the holding in Adoptive Couple v. Baby Girl, which turned on interpretations of the Indian Child Welfare Act of 1978, will affect few people. The facts of the case were ordinary enough: An expectant mother broke off her engagement to her fiancé, who subsequently texted her that he would give up his parental rights rather than pay support for the child. She gave up the baby girl for adoption, and the baby found loving and supportive parents.

What made it a federal case was that the biological father is a member of the Cherokee nation, making the girl 3/256ths Cherokee. (That’s 1.2 percent, if you’re counting, and yes, it’s more than Senator Elizabeth Warren is.) Those facts invoked the ICWA, a law designed to remedy the shameful history of states forcibly taking American Indian children from their birth parents and “assimilating” them into white American families.

‘Best Interests’

When the adoptive parents told the biological father of their intent to adopt -- the child was by then four months old - - the father said, for the first time, he wanted to keep the child. That assertion ordinarily would have stopped an adoption in its tracks. The ICWA bars the adoption of an Indian child absent a showing beyond a reasonable doubt that the “continued custody of the child by the parent or Indian custodian is likely to result in serious emotional or physical damage to the child.” It also requires that efforts be made “to prevent the breakup of the Indian family.” Any ordinary reading of these provisions would have granted custody to the father.

Yet Justice Samuel Alito -- joined by Chief Justice John Roberts and Justices Clarence Thomas, Anthony Kennedy and Stephen Breyer (the sole liberal here) -- thought otherwise. In a remarkable decision, the majority first said that custody wasn’t “continued” because the biological father never had custody in the first place. Then it said that no efforts had to be made to prevent “the breakup of the Indian family” because there was no family to speak of. To put it bluntly, the court denied that the biological father was a father in any meaningful sense.

What was going on here? As a brutally direct dissent by Justice Sonia Sotomayor made clear, these lawyerly contortions distorted the usual rules of statutory interpretation. The court was bending over backward to deny the Indian father his legal rights.

You don’t have to dig too deeply to uncover clues that explain the majority’s holding. The opinion noted that, had the father not been Indian, the whole case wouldn’t have arisen, because ordinary “best interests of the child” analysis -- the hallmark of family law -- would have given the child to her adoptive parents. Conservatives have never liked ICWA, with its special granting of rights to Indians on the basis of their tribal sovereignty and the associated whiff of racial discrimination. But equal protection wasn’t the majority five’s motivating factor. Rather, it was their embrace of the norms of parental adoption and a distaste for a law that prefers biological parents to adopted ones.

Contemporary Morals

In a detail that should (in principle) have had no bearing on the case, Alito’s decision noted that the adoptive parents attended the baby’s birth, and that the “Adoptive Father even cut the umbilical cord.” When lower courts ruled in favor of the biological father, Alito noted, the girl was, at 27 months, handed over to a man “whom she had never met” -- presumably because the adoptive parents did not allow him to meet her. The court also repeatedly said that the biological father had “abandoned” his daughter prior to her birth. It’s true that he initially relinquished parental rights to the mother, but he also asserted parenthood within a day of learning about the proposed adoption.

Most striking, the ruling’s statutory interpretation made sense only against the backdrop of the court’s strong presumption against the biological father. To say that there could be no continued custody because he never had custody makes sense only because the adoption process began even before the baby’s birth. To deny there was ever a “family” that included the biological father rests on the same conception. These views reflect a contemporary moral perspective that the adoptive relationship can wholly replace the biological one -- and can be better for the child.

Antonin Scalia, increasingly the paleoconservative on the court, stuck with the now-apparently-outmoded conservative view that biology matters. He joined Sotomayor’s dissent, which can be explained by his customary textual fidelity, but also spoke his mind in his own short dissent. The majority, he said, “needlessly demeans the rights of parenthood” that were long respected by the common law. The best interests of the child, he pointed out, are not in fact considered when a baby is born unless there is some controversy about custody -- the child ordinarily stays with its biological parents. Some children, he said, would “be better off raised by someone else,” but our laws respect the rights of birth parents.

Time has passed Scalia by. The younger generation of conservatives is comfortable with adoption and has adopted mainstream American views on the subject. Scalia has nine children and 28 grandchildren. Alito and Roberts have two children each, and Roberts’s are adopted. To the younger conservatives, an adoptive parent is a true parent, and any law that interferes with that belongs on the junk pile.

(Noah Feldman, a law professor at Harvard University and the author of “Cool War: The Future of Global Competition,” is a Bloomberg View columnist. Follow him on Twitter at @NoahRFeldman.)

To contact the writer of this article: Noah Feldman at noah_feldman@harvard.edu.

To contact the editor responsible for this article: Tobin Harshaw at tharshaw@bloomberg.net.