Polygamy and the Latter Day Saint movement

Polygamy (more specifically, polygyny, called plural marriage by Mormons in the 19th century or the Principle by modern fundamentalist practitioners of polygamy) was taught by leaders of The Church of Jesus Christ of Latter-day Saints (LDS Church) for more than half of the 19th century, and practiced publicly from 1852 to 1890 by between 20 and 30 percent of Latter-day Saint families.

The Latter-day Saints' practice of polygamy has been controversial, both within Western society and the LDS Church itself. America was both fascinated and horrified by the practice of polygamy, with the Republican platform at one time referencing "the twin relics of barbarism—polygamy and slavery." The private practice of polygamy was instituted in the 1830s by founder Joseph Smith. The public practice of plural marriage by the church was announced and defended in 1852 by a member of the Quorum of the Twelve Apostles, Orson Pratt, by the request of church president Brigham Young.

For over 60 years, the LDS Church and the United States were at odds over the issue: the church defended the practice as a matter of religious freedom, while the federal government aggressively sought to eradicate it, consistent with prevailing public opinion. Polygamy was probably a significant factor in the Utah War of 1857 and 1858, given the Republican attempts to paint Democratic President James Buchanan as weak in his opposition to both polygamy and slavery. In 1862, the United States Congress passed the Morrill Anti-Bigamy Act, which prohibited plural marriage in the territories. In spite of the law, Mormons continued to practice polygamy, believing that it was protected by the First Amendment. In 1879, in Reynolds v. United States, the Supreme Court of the United States upheld the Morrill Act, stating: "Laws are made for the government of actions, and while they cannot interfere with mere religious belief and opinion, they may with practices."

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