Tuesday, during the federal trial to decide the constitutionality of Proposition 8, the defense's second – and final – witness surprised when he testified that legalizing gay marriage would “improve the well-being of gay and lesbian households and their children.”

The trial, now in its third week, began with the emotional testimony of a gay and a lesbian couple, each of which has been denied the right to marry in California because of Proposition 8, the gay marriage ban approved by voters in 2008.

David Blankenhorn, founder and president of the conservative think tank Institute for American Values, also told the court that homophobia is a “real presence” in our society. He said, I “regret and deplore it, and wish it to go away.”

But he also asserted that the best environment for children is a heterosexual marriage.

“The optimal environment for children is if they're raised from birth by their own natural mother, who is married to their own natural father,” he testified.

Blankenhorn has written extensively on the subject of marriage and fatherhood. He is the author of The Future of Marriage and Fatherless America: Confronting our Most Urgent Social Problem.

Last February, Blankenhorn, along with co-author Jonathan Rauch, made a bit of a splash in the gay blogosphere when his A Reconciliation on Gay Marriage op-ed appeared in the New York Times. The piece offered a compromise of sorts on gay marriage.

“It would work like this: Congress would bestow the status of federal civil unions on same-sex marriage and civil unions granted at the state level, thereby conferring upon them most or all of the federal benefits and rights of marriage. But there would be a condition: Washington would recognize only those unions licensed in states with robust religious-conscience exceptions, which provide that religious organizations need not recognize same-sex unions against their will. The federal government would also enact religious-conscience protections of its own. All of these changes would be enacted in the same bill.”

During a sometimes heated cross-examination, David Boies, a lawyer for the plaintiffs, hammered out more concessions from the defense's final witness.

Without elaboration, Blankenhorn said that gay marriage in the United States would make the country “more American.”

Lawyers in favor of gay marriage have argued that proponents of Proposition 8 approved the measure out of animus towards gay men and lesbians. The defense says limiting marriage to heterosexual unions fosters a stable environment to raise children.

Blankenhorn's testimony drove home their argument: “Marriage is a socially approved sexual relationship between a man and a woman. Marriage does a number of things, but the most important thing it does is regulate affiliation. It establishes who are the child's legal and social parents.”

The trial resumes Wednesday, when lawyers are expected to present final evidence, but Chief US District Judge Vaughn R. Walker is not expected to hear closing arguments. Walker has said he wants to review the evidence first.