After the U.S. Civil War, federally appointed Utah territorial officials made polygamy and the Mormon Church’s control of the political and legal systems the centerpiece of their complaints in Washington. With the passage of the Poland Act of 1874, which for the first time since 1862 expanded the reach of federal power in the Utah Territory, the stage was set for a judicial confrontation between Mormons in Utah and the federal government. This played out in Reynolds v. United States, which went to the U.S. Supreme Court in 1878.

From the Introduction

In the mid-nineteenth century, an extraordinary contest over religion and law took shape. The conflict began with the announcement in 1852 by Brigham Young, president and prophet of the Church of Jesus Christ of Latter-day Saints, popularly called Mormons. Young proclaimed that Mormons believed in and practiced polygamy – known to the faithful as the “celestial” law of plural marriage, or “Patriarchal Marriage,” or simply “the Principle.” In 1890, however the church formally announced that it would no longer counsel the Saints to disobey the laws of man by practicing polygamy. The public announcement of the intention to abandon all claims to legal right eventually (although with aftershocks that lasted into the twentieth century) satisfied the great majority of those who opposed polygamy (antipolygamists) that their goal had been achieved at last, and that American civilization had been saved from a potent and destructive “barbarism.”