That's not the entire case though. The Missouri statute seems coextensive with the federal statute, which as noted prohibits discrimination based on sex, rather than other state statutes, like Colorado, that also prohibit it on sexual orientation. Recently, parties have been arguing, with some success, that the federal Civil Rights Act covering sexual discrimination also prohibits sexual orientation discrimination. For example, a skydiving instructor was fired after telling one of the divers he was gay (ironically, this student was a heterosexual woman, so exactly why she objected to him strapping himself onto her back is unclear to me). The 2nd Circuit Court of Appeals, one level below the Supreme Court, ruled that the CRA extends to sexual orientation behavior.