Dan Cathy, the CEO of Chick-fil-A, is a self-described Christian businessman, who proudly runs his fast-food chain according to his own vision of Christian principles. His stores close on Sundays, for instance, and the company gives money to nonprofits that support limiting marriage to unions between a man and a woman. A couple of weeks ago, Cathy explained this in an interview with the Baptist Press. “We are very much supportive of the family — the biblical definition of the family unit,” he said. “We are a family-owned business, a family-led business, and we are married to our first wives. We give God thanks for that.”

For this reason, Boston Mayor Thomas Menino has urged Chick-fil-A to “back out” of its “plans to locate in Boston.” And Chicago Mayor Rahm Emanuel says Chick-fil-A has no place in the city of Chicago.

“Chick-fil-A’s values are not Chicago values. They’re not respectful of our residents, our neighbors and our family members. And if you’re gonna be part of the Chicago community, you should reflect Chicago values,” Emanuel said, according to the Chicago Sun-Times. Alderman Joe Moreno says he will seek to block a permit for Chick-fil-A in Chicago’s Logan Square neighborhood. “Same-sex marriage, same-sex couples — that’s the civil rights fight of our time. To have those discriminatory policies from the top down is just not something that we’re open to,” Moreno said.

No evidence has been presented to suggest that Chick-fil-A discriminates against gay or lesbian customers or employees. There is nothing to suggest that the company has broken the law in any way. In his comments to the Baptist Press, Cathy did not even mention same-sex marriage. He simply said that he and his company supported traditional marriage. The only issues at play are the personal view of the owner of the restaurant chain and the philanthropic efforts of the private company.

That puts the political leaders of Boston and Chicago in tricky legal waters. Generally speaking, governments have a responsibility to not discriminate against businesses on the basis of personal beliefs, just as restaurant chains cannot discriminate against employees on the basis of personal beliefs (or sexual orientation). “It’s very problematic,” explains Alan Weinstein, a law professor at Cleveland State University who studies municipal zoning. “The political, ideological and theological views of a person seeking the land-use permit are entirely irrelevant.” Mayors are free to speak their minds, and city councils can pass resolutions expressing their views, but a judge would almost certainly toss out any punitive action taken against the restaurant chain on such grounds, Weinstein says.

And in other contexts, the same sort of tactics would be clearly repugnant to the liberal constituencies of Menino and Emanuel. Would it be O.K. for a mayor to reject a business owned by a Muslim because the mayor was offended by the teachings of Islam? Would it be O.K. for the mayor of a coal community to deny a building permit to a newspaper that planned to write critically of the coal industry? (The Boston Globe editorial board makes a similar point here.)

Robust public disagreements over issues like the definition of marriage are a symptom of a functioning democracy, not evidence of its dysfunction. A recent poll in Massachusetts found that 30% of the state believes same-sex marriage should be illegal. In the Chicago area, 42% of residents support same-sex marriage, while the same number, 42%, oppose it. (Indeed, Emanuel’s depiction of “Chicago values” is misleading; the city is divided on the issue of marriage.) Presumably, many business owners in both states are among those who oppose same-sex marriage. Should those businessmen and women worry that their hopes for city permits or mayoral cooperation could be jeopardized if they express their opinions publicly?

Consumers have every right to patronize or boycott any restaurant they choose for any reason. But a government’s responsibility is different. It is one thing for big-city politicians to voice their own views. It is another thing for them to threaten businesses with the power of their elected office for not sharing those views.

UPDATE: Boston Mayor Menino announced on July 26 that he will not seek punitive action against Chick-fil-A. “I can’t do that. That would be interference to his rights to go there,” Menino said, referring to CEO Cathy, according to the Boston Herald. “I make mistakes all the time. That’s a Menino-ism.”