The University of California's Hastings Law School says the Christian Legal Society's policy discriminates against gays and non-Christians.
The society requires officers and voting members to sign a statement of faith and agree that "Christians should not engage in sexual conduct outside of a marriage between a man and a woman."
The school says official campus groups, which are eligible for funding and other benefits, may not exclude people because of religious belief or sexual orientation.
The Christian Legal Society responds that its code addresses conduct, not orientation. The CLS also argues that groups shouldn't be forced to allow people who don't share their beliefs to become leaders.