Wooley v. Maynard
In Wooley v. Maynard, 430 U.S. 705 (1977), the U.S. Supreme Court held that the State of New Hampshire cannot force an objecting resident to display on his license plates the state motto, "Live Free or Die."
The court held that the First Amendment protects against this compelled speech. The State may not "'invad[e] the sphere of intellect and spirit which it is the purpose of the First Amendment of our Constitution to reserve from all official control.'" Wooley v. Maynard, 430 U.S. at 715 (quoting West Virginia Bd. of Ed. v. Barnette, 319 U.S. 624, 642 (1943)).