Since opening statements were delivered by state and plaintiff attorneys a week ago, both sides have produced a number of expert witnesses who have testified largely on comparisons between heterosexual and same-sex couples, their households and how they influence children.

Tuesday began with the plaintiffs’ attorney questioning Mark Regnerus, an associate professor of sociology from the University of Texas at Austin, whose controversial 2012 study has been cited by opponents of same sex marriage in numerous cases across the country.

Regnerus, a witness for the state, authored a study that drew comparisons from now-adult children from heterosexual and same-sex households and compared a number of factors from their lives. 

While an initial witness for the plaintiffs, Michael Rosenfeld, authored a study that found no significant differences in outcomes for children raised by same-sex parents, Regnerus’ study found that outcomes were significantly worse.

American Civil Liberties Union attorney Leslie Cooper cited Regnerus’ personal opposition to same-sex marriage and the funding he has received from groups opposed to marriage equality. Other expert witness previously expressed concerns with the methodology of Regnerus’ study.

In the redirect examination, Cooper brought up a passage in Regnerus’ study that emphasized the difference between correlation and causation.

“I am thus not suggesting that growing up with a lesbian mother or gay father causes suboptimal outcomes because of the sexual orientation or sexual behavior of the parent,” the study said. “Rather, my point is more modest: the groups display numerous, notable distinctions, especially when compared with young adults whose biological mother and father remain married.”

Regnerus said he didn’t have an opinion about whether gay or lesbian parents should be allowed should adopt children.

The state attorneys also introduced Joseph Price, an associate professor in economics from Brigham Young University. He, like Regnerus, published an analysis with results that contrast the research of other experts that have testified in the trial such as Rosenfeld.

Although the experts conducted their research around essentially the same issue, discrepancies arose around what types of households should be included in the samples of each study, and how the various inclusions and exclusions altered results.

The state spent the vast majority of the afternoon questioning Price about the statistical minutiae that resulted in differences between the studies. Price said in his opinion a child is best raised in a household with two heterosexual, biologically-related parents.

In the beginning of the state’s cross-examination of Price, Attorney Dana Nessel worked to discredit Price by discussing his affiliations to various conservative thinktanks and groups opposed to same-sex marriage.

Nessel, in her questions, argued that Price’s economics background had little to do with the sociological focus of the study.

The state will continue examining witnesses throughout this week, followed by concluding arguments from both sides. Judge Friedman is then expected to rule on the case.