SAN FRANCISCO (Reuters) - A roommate-finding site cannot require users to disclose their sexual orientation, a U.S. appeals court ruled on Thursday, in the latest skirmish over whether anti-discrimination rules apply to the Web.

The U.S. 9th Circuit Court of Appeals said Roommates.com, which obliges users to list their sexual orientation, was different than Internet sites where people can volunteer or withhold personal information.

To inquire electronically about sexual orientation would not be different from asking people in person or by telephone if they were black or Jewish before conducting business, the panel said in an 8-3 ruling that partly overturns a lower federal court decision.

“If such screening is prohibited when practiced in person or by telephone, we see no reason why Congress would have wanted to make it lawful to profit from it online,” 9th Circuit chief judge Alex Kozinski wrote. “Not only does Roommate ask these questions, Roommate makes answering the discriminatory questions a condition of doing business.”

Roommates.com says it offers more than 100,000 rental listings on its site across the United States and is owned by Roommate.com LLC.

The court contrasted such requests for information with online search engines such as Google, which could allow people to search for terms such as “white roommate.”

‘CLOSE CASES’

“Web sites are complicated enterprises, and there will always be close cases where a clever lawyer could argue that something the Web site operator did encouraged the illegality,” Kozinski wrote. “Such close cases, we believe, must be resolved in favor of immunity.”

“Where it is very clear that the Web site directly participates in developing the alleged illegality -- as it is clear here with respect to Roommate’s questions, answers and the resulting profile pages -- immunity will be lost.”

A Roommates.com section allowing users to add additional comments of their choosing is immune from liability as outlined in the 1996 Communications Decency Act, the San Francisco-based court found.

Congress “didn’t intend to prevent the enforcement of all laws online,” the court said. “Rather, it sought to encourage interactive computer services that provide users neutral tools to post content online to police that content without fear that ... they would become liable for every single message posted by third parties on their Web site,” it said.

Three judges dissented, saying the court was creating a dangerous precedent and future confusion for Internet firms.

“The majority’s unprecedented expansion of liability for Internet service providers threatens to chill the robust development of the Internet that Congress envisioned,” Judge Margaret McKeown wrote.

Roommates.com “should be afforded no less protection than Google, Yahoo, or other search engines.”

The Fair Housing Council of San Fernando Valley and the Fair Housing Council of San Diego filed suit against the Web site, claiming it violated the Fair Housing Act and various state laws.