Cleveland v. United States (1946) upheld the convictions of a
fundamentalist group of polygamous Mormons. Polygamy is not historically
protected by the First Amendment.

In Davis v. Beason (1890) upheld a law withdrew the right to vote from
polygamists. The Court said the First Amendment freedom of religion must be
subordinate to laws.

In Murphy v. Ramsey (1885), the Supreme Court upheld a federal law that
denied polygamists the right to vote, denying that the law was an ex post
facto provision.

In Musser v. Utah, 333 U.S. 94 (1948), Justice Robert Jackson wrote an opinion for the U.S. Supreme Court in which he vacated the conviction of three men for advocating polygamy and remanded the case back to Utah’s courts. Jackson wrote that the state law against polygamy was “no narrowly drawn statute,” and said its vagueness

In Reynolds v. United States (1879), the Supreme Court ruled unanimously
that a federal law prohibiting polygamy did not violate the free exercise
clause of the First Amendment.