In San Antonio, where the mayor is rising Democratic star Julian Castro, a broad new anti-discrimination ordinance under consideration may catch opponents of same-sex marriage in its net, in what opponents consider a disturbing infringement on liberty of conscience. The ordinance would prohibit bias toward people on account of sexual orientation. Opponents are concerned that opposition to same-sex marriage or other viewpoints about homosexuality would be considered bias. “If you, for instance, oppose same-sex marriage, that’s going to be interpreted as opposing someone based on sexual orientation,” explains Jeff Mateer, general counsel for the Liberty Institute, an organization that focuses...