The First Amendment protects speech, and it protects speakers from compelled speech. Generally, you can't be forced to say or sign anything – a prayer, the Pledge of Allegiance, a loyalty oath, that goes against your deeply held beliefs. But all speech protections are contingent: just as some speech has no constitutional protection, governments and in some cases, employers, may compel certain types of speech. Laws may dictate the content of product labels or other aspects of advertising; employers may require workers to follow scripts or repeat certain formulas; some loyalty oaths may be required; and federal law requires English as the language of air traffic control. We look at three examples of compelled speech in this chapter: the presidential oath of office, prescribed in the US Constitution; the Miranda warning, the caution that police must give to anyone under arrest before they may question them. And statutes that define their own words. Such definitions require us to accept a particular meaning and reject alternatives, and as such, they constitute compelled speech. We see the problems that ensued when the US government enacted a law defining "marriage" as the "union of one man and one woman," a law that was ultimately ruled unconstitution by the US Supreme Court in Windsor v. US.