Testimony in the federal Proposition 8 trial will conclude Wednesday, with attorneys for two gay couples rigorously attacking defense expert witnesses’ assertions on the purported harms of marriage equality. Among them: that gay marriage will lead to higher divorce rates and out-of-wedlock births for heterosexuals.

However, Prop. 8 proponents on Tuesday appeared to bolster what plaintiffs in the case have argued all along: that there is no credible evidence pointing to any negative effects on opposite-sex couples and their families if gays were allowed to marry. In fact, for the third time in the trial, defense expert witness testimony corroborated plaintiffs’ argument that same-sex marriage can only serve to strengthen gay couples’ relationships and lead to a stronger familial foundation for their children.

Following the conclusion of testimony, Judge Vaughn Walker is expected to review evidence and schedule closing arguments in the coming weeks.

Defense witness and Institute for American Values president David Blankenhorn told the court Tuesday afternoon that the core purpose of marriage is to fulfill a child’s need “to be emotionally, morally, practically, and legally affiliated with the woman and the man whose sexual union brought the child into the world.”

“That is not all that marriage is or does,” Blankenhorn said. “But nearly everywhere on the planet, that is fundamentally what marriage is.”