Todd and Mark Wathen's fight against the establishments highlights what advocates say is a growing battle between religious freedoms and gay civil rights.

The Chicago Tribune reported that  when the couple approached the Beall Mansion in Alton in southern Illinois earlier this year, they received an email response that the inn "will just be doing traditional weddings." A similar message came from the owner of the Timber Creek Bed and Breakfast in Paxton in central Illinois, who said the inn would "never host same-sex civil unions."

"We believe homosexuality is wrong and unnatural based on what the Bible says about it," the email from Timber Creek's owner said. "If that is discrimination, I guess we unfortunately discriminate."

Steven Amjad, an attorney representing Timber Creek, said religious freedoms are guaranteed by the state constitution.

Andrew Koppelman, a professor of political science and law at Northwestern University, said the question is whether the state's Religious Freedom Restoration Act — which protects religious freedoms from government intrusion — can trump the state's Human Rights Act, which includes the protection of people based on sexual orientation.

"The hotels seem pretty clearly in violation of the Human Rights Act," Koppelman said. "And if you're going to say that somebody is exempted from the human rights law under the Religious Freedom Restoration Act, that would mean that people could discriminate based on religious views. It's a slippery slope."

As civil union and same-sex marriage laws have been enacted in states across the country, similar legal cases have surfaced. In Vermont, for example, a lesbian couple has sued a bed and breakfast for having a "no-gay reception policy."