Speaker of the House John Boehner, courtesy of the Speaker's office.

A Republican-controlled congressional body this week used a controversial new parenting study to argue that the Defense of Marriage Act is constitutional.

The Bipartisan Legal Advisory Group of the U.S. House of Representatives, commonly known as BLAG, filed a brief Tuesday with the Ninth Circuit Court of Appeals in the case of Karen Golinski, who is suing to force the federal government to recognize her marriage. BLAG has been involved in this and other marriage cases since last year, when President Obama decided the Department of Justice would no longer defend the constitutionality of a key section of DOMA.

BLAG’s brief marks the second time the study — which was conducted by University of Texas professor Mark Regnerus with the financial backing of socially conservative groups — has been used to defend DOMA in the case. The day after Regnerus’ study was released to the public last month, a conservative medical group highlighted it in a  “friend of the court” brief. The American College of Pediatricians filed that brief at the request of the Alliance Defending Freedom, an influential religious right legal organization.

In its June 11 amicus brief, the American College of Pediatricians had referred to Regnerus’ study as “the most current research on child outcomes for children raised by same-sex couples” and wrongly asserted that Regnerus had found a number of “statistically significant differences where children raised by two women fared worse than children raised by married biological parents.”

In fact, Regnerus’ study has been widely criticized for comparing children raised by intact biological families to children raised by parents who had a same-sex relationship at some point, regardless of whether the child was actually raised by a stable, same-sex couple.

Golinski, who is represented by the Lambda Legal Defense and Education Fund, responded in a brief earlier this month defending previous research concluding that children raised by same-sex parents fared no worse than those raised by opposite-sex parents. Golinksi’s brief criticized the American College of Pediatricians’ use of Regnerus’ study:

[The American College of Pediatricians] cites a recent paper by Mark Regnerus purporting to present empirical evidence of differences in outcomes for children raised by lesbian and gay parents. … This study, however, compared children of “intact biological famil[ies]” not to children raised by “intact” same-sex couples but instead primarily to children raised by single parents and in unstable family settings, with loosely-applied criteria for categorizing a parent as lesbian or gay. The paper itself concedes that it cannot answer any “questions of causation.” This paper does nothing to undercut the consistent social science findings over decades of research.

On Tuesday, BLAG answered with a brief that cites Regnerus’ study in defending what it describes as one of the rational bases behind DOMA: “the centuries-old wisdom that children generally benefit from being raised by their own biological mothers and fathers, and that law and government should encourage and support that outcome.”

BLAG’s brief describes the Regnerus study as one of “two significant studies” published in recent weeks “undermining Ms. Golinski’s social science theory.” BLAG adds:

Unlike virtually all of the previous studies in this area, the Regnerus study included a representative sample that was large enough to draw statistically powerful conclusions regarding comparative outcomes of people whose parents had homosexual relationships and those who were raised by their married biological mothers and fathers—and it discovered that the former group reported significantly worse outcomes on a large number of key indicators.

BLAG also pushes back on criticism of Regnerus’ study, citing a joint statement from 18 social scientists who have defended it. BLAG’s brief further states:

In any event, the study’s alleged shortcoming—that adults raised from infancy by same-sex couples are so rare that it is impossible to obtain a large sampling of them … “despite significant efforts” to do so… —only highlights the fact that all of the research in this field is in its infancy. That fact underscores the rationality of Congress’ decision to proceed with caution.

The other recent study BLAG cites in support of the premise that children are better off when raised by two heterosexual parents was published in the Journal of Marriage and Family in May. That study, authored by Daniel Potter of the American Institutes for Research, found that children raised in same-sex-parent families scored lower on academic tests than children raised in two-parent households by a straight couple. Potter found that children raised by same-sex couples scored similarly to children in other types of “nontraditional families” — meaning families that involve stepparents, single parents, cohabiting parents, or another nontraditional structure.