[2] The LDS Church, believing that the law unconstitutionally deprived its members of their First Amendment right to freely practice their religion, chose to challenge the Morrill Anti-Bigamy Act.

The First Presidency decided to furnish a defendant to establish a test case to be brought before the United States Supreme Court, to determine the constitutionality of the anti-bigamy law.

He provided the United States Attorney with numerous witnesses who could testify of his being married to two wives, and was indicted for bigamy by a grand jury on June 23, 1874.

In 1875, Reynolds was convicted and sentenced to two years in prison at hard labor (a provision not included in the statute) and a fine of five hundred dollars.

Previously, U.S. Attorney William Carey promised to stop his attempts to indict general authorities during the test case.

However, when Carey failed to keep his promise and arrested George Q. Cannon, LDS Church leaders decided that they would no longer cooperate with him.

The trial court refused this request and instructed the jury that if they found that Reynolds, under religious influence, "deliberately married a second time, having a first wife living, the want of consciousness of evil intent—the want of understanding on his part that he was committing crime—did not excuse him, but the law inexorably, in such cases, implies criminal intent."

Reynolds's attorneys, George W. Biddle and Ben Sheeks, appealed the Utah Territorial Supreme Court decision to the U.S. Supreme Court, consisting of Chief Justice Morrison Remick Waite, and Associate Justices Joseph P. Bradley, Nathan Clifford, Stephen Johnson Field, John Marshall Harlan, Ward Hunt, Samuel Freeman Miller, William Strong, and Noah Haynes Swayne.

At a subsequent day of the term, on a petition for rehearing, it was pointed out that Reynolds' sentence to "hard labor" was not a part of the statute.

The cause is remanded, with instructions to cause the sentence of the District Court to be set aside and a new one entered on the verdict in all respects like that before imposed, except so far as it requires the imprisonment to be at hard labor.

The court held that universal education and press reports made it hard to find jurors who had not formed some opinion.

Reynolds had argued that the jury had been improperly instructed by the judge when he told them that they "should consider what are to be the consequences to the innocent victims of this delusion".

George Q. Cannon, representative of the territory, wrote in response to this decision:[7] Our crime has been: We married women instead of seducing them; we reared children instead of destroying them; we desired to exclude from the land prostitution, bastardy and infanticide.

Jefferson wrote in return to the Baptists that the United States Bill of Rights prevents the establishment of a national church, and so they did not have to fear government interference in their right to expressions of religious conscience: Believing with you that religion is a matter which lies solely between Man & his God, that he owes account to none other for his faith or his worship, that the legitimate powers of government reach actions only, and not opinions, I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should "make no law respecting an establishment of religion, or prohibiting the free exercise thereof", thus building a wall of separation between Church & State.