On the second day of the trial of Proposition 8, lawyers for the plaintiffs argued that discrimination was at the root of the gay marriage ban.

Two Ivy League historians testified on the discrimination faced by gay men and lesbians on Tuesday.

The trial – the first federal case to challenge the constitutionality of a gay marriage ban – began Monday in San Francisco with the emotional testimony of a gay and a lesbian couple who have been denied the right to marry in California because of Proposition 8, the gay marriage ban approved by voters in 2008.

Harvard University professor Nancy Cott, an expert on marriage in the United States, and George Chauncey, a Yale University historian who has written about anti-gay discrimination testified for the plaintiffs. Chauncey is the author of Why Marriage? The history shaping today's debate over gay equality and Gay New York: Gender, Urban Culture, and the Making of the Gay Male World, 1890 – 1940.

Cott's testimony was designed to poke holes at arguments made by Proposition 8 supporters in their opening statements, including the argument that marriage is designed primarily for procreation.

“The institution of marriage has always been at least [as much] about supporting adults as it has about supporting minors,” she testified, then added, “There has never been a requirement that a couple produce children to have a valid marriage.”

Chauncey testified on more than 100 years of discrimination against gay men and lesbians, telling the court that “demonic stereotypes” of gay people continue today, especially with folks who interact with children such as teachers and parents.

When asked, Chauncey agreed that negative gay stereotypes had been used in the campaign to approve Proposition 8. While admitting that the campaign did not call gay people child molesters, he said its focus on kids implied as much.

Proponents for Proposition 8 attempted to discredit both witnesses by labeling them gay rights advocates. Within minutes of leaving the stand, Proposition 8 counsel Andrew Pugno called Cott's testimony “a disaster for the plaintiffs” during a midday press conference.

Lawyers return to the courtroom on Wednesday.