As I report in today’s article, Chief U.S. District Judge Vaughn Walker of San Francisco has set a trial date for the federal constitutional challenge to Proposition 8’s ban on same-sex marriage.

He also rejected motions to intervene from a trio of gay-rights groups – the Our Family Coalition, Lavender Seniors and Parents, Families, & Friends of Lesbians and Gays (PFLAG) – represented by the American Civil Liberties Union of Northern California, Lambda Legal and the National Center for Lesbian Rights, as well as from the conservative Campaign for California Families.

And in arguing for and against both, attorneys again highlighted some of the tactical rifts that have formed on both sides of the same-sex marriage debate.

An attorney for the Campaign for California Families argued that Prop. 8’s proponents, who’ve already successfully intervened as proponents in this case (as Gov. Arnold Schwarzenegger and various state and county defendants basically have declined to defend the measure’s constitutionality), may generally share CCF’s opposition to same-sex marriage but are making too many concessions in trying to defend the ban.

Stipulating, or leaving room for a future stipulation, that gays and lesbians form committed relationships, contribute to society just as heterosexuals do, don’t suffer from a psychological illness or disorder, and shouldn’t be encouraged to try to change their sexual orientations are examples of how the proponents are ceding too much ground, she said, and could compromise CCF’s efforts not only to keep marriage exclusively heterosexual but also to repeal existing domestic partnership laws granting certain marriage-like rights to same-sex couples.

But a lawyer for Prop. 8’s proponents urged Walker to deny CCF’s motion to intervene, saying doing so would cause “experts to multiply like locusts” and bog down the case’s trial in “battles that can’t be won.”

On the other side, an ACLU attorney argued his coalition of clients should be allowed to intervene because of the broad range of detailed experience their members have with discrimination and the desire to marry.

But former U.S. Solicitor General Ted Olson, representing the case’s plaintiffs – specific couples denied the right to marry – said that although he respects the coalition’s legal counsel and values their advice and support, letting them intervene could dilute his clients’ control of their legal strategy while complicating and slowing the case’s progress. In a recent brief, he’d noted that the Our Family Coalition had argued against this lawsuit in the first place, calling it a risky and premature gambit and preferring to pursue a new ballot measure to repeal Prop. 8.