Proponents of California's gay marriage ban took control of the trial considering the constitutionality of the measure after plaintiffs rested their case on Monday. The trial is now in its third week in a San Francisco courtroom.

Witnesses for the defense were under pressure to chip away at arguments made by the plaintiffs over the past two weeks. Specifically, that the ban, known as Proposition 8, was approved out of animus towards gay men and lesbians.

Their first witness, Dr. Kenneth P. Miller, a professor of government at Claremont McKenna College in Southern California, said that while proponents voted twice to define marriage as a heterosexual union, they did not move to strip away other laws that recognize gay unions, including domestic partnerships.

“California voters have not used the initiative process nor the popular referendum to repeal or limit the Legislature's other broad expansions of LGBT rights,” Miller testified.

Miller's Claremont McKenna College bio states he is an expert in the California initiative process.

Defense lawyer David Thompson lobbed at him the names of prominent California politicians, including Governor Arnold Schwarzenegger, a Republican, Attorney General Jerry Brown, and Representative John Garamendi, and Miller responded that each was an ally to the gay and lesbian community.

In a cutting cross examination, David Boies hit hard, questioning Miller's credentials as an expert witness on gay and lesbian political clout. He pointed out that Miller has published only one paper on the subject. Boies asked whether Miller knew what the Mattachine Society was during an earlier deposition. Miller agreed he had not.

The trial, the first to be argued in federal court, will likely end on Tuesday. Chief U.S. District Judge Vaughn R. Walker's calendar shows he's unavailable starting Wednesday. Walker has said he will hear closing arguments at a later date, possibly in February.

Earlier Monday, lawyers for the plaintiffs submitted their final pieces of evidence. In one video, Tony Perkins, president of the Family Research Council, a group that opposes gay rights, says that if gay marriage is legal, then it must be taught as moral behavior in public schools. In another video, a pastor says that “polygamists are going to use that exact same argument [as gay marriage advocates] and they're going to win.” And a woman argues in favor of Proposition 8 by saying that pedophiles would be allowed to marry children if the ban is not approved.