The ruling reverses a lower court decision that denied the group a preliminary injunction re-establishing its status while the lawsuit proceeds.

The Christian Legal Society sued Southern Illinois University in 2005 after the school revoked the group's registered status, meaning it no longer could use the university's facilities or name and was ineligible for school funding. The group claimed the university's decision violated its First Amendment rights to free speech and free exercise of religion.

The university said the society's requirement that members adhere to basic Christian beliefs violates the school's affirmative action policy as well as a Board of Trustees policy stating that student organizations must follow all "federal or state laws concerning nondiscrimination and equal opportunity."

But in its ruling Monday, the 7th Circuit Court of Appeals said the university "failed to identify which federal or state law it believes (Christian Legal Society) violated."

Messages seeking comment were left after business hours Monday for university general counsel Jerry Blakemore and Christian Legal Society attorney Casey Mattox.

Mattox has said the university began looking into the chapter's requirements after a student who never attended a Christian Legal Society meeting read about its policies in a law journal and brought them to administrators' attention. No student was denied a membership or leadership position within the group because of his or her religious beliefs, he said.

Christian Legal Society, based in Annandale, Va., is a nationwide association of more than 3,400 Christian lawyers, law students, law professors and judges with chapters in more than 1,100 cities across the country, according to its Web site. The university's chapter had fewer than 12 members, Mattox said.