The First Amendment's guarantee of free exercise of religion protects religious beliefs and opinions but does not protect overt acts that violate generally applicable criminal laws, even if those acts are committed in pursuance of a religious duty; thus, a religious belief cannot be a defense to a charge of bigamy.

The case arose from the conflict between federal anti-bigamy laws and the practice of polygamy by members of the Church of Jesus Christ of Latter-Day Saints (Mormon Church) in the Utah Territory. The federal government sought to suppress polygamy, viewing it as detrimental to social order, while many Mormons considered it a religious obligation. This tension led to prosecutions under federal statutes, with defendants often invoking religious freedom as a defense.

• George Reynolds, a resident of Utah Territory and a member of the Mormon Church, was charged with bigamy for marrying Amelia Jane Schofield while already being married to Mary Ann Tuddenham.
• At trial, Reynolds admitted to the second marriage and presented evidence that the doctrine of polygamy was a religious tenet of his church, enjoined by what he believed to be divine revelation, and that he had received church sanction for the marriage.
• The grand jury that indicted Reynolds consisted of fifteen persons, in accordance with Utah territorial law, not the minimum of sixteen required by federal statute for U.S. Circuit and District Courts.
• During jury selection, Reynolds challenged jurors for cause due to pre-formed opinions; these challenges were overruled. The prosecution successfully challenged other jurors for cause because they practiced polygamy.
• The trial court admitted the testimony of Amelia Jane Schofield given at a previous trial of Reynolds for the same offense (under a different indictment), after evidence suggested Reynolds was instrumental in her absence from the current trial.
• The trial court refused Reynolds's request to instruct the jury that he should be acquitted if he entered the second marriage based on a sincere religious belief and duty. Instead, the court instructed that such belief did not excuse the crime if he deliberately married a second time while his first wife was living.
• The court also commented on the societal consequences of polygamy in its charge to the jury.
• Reynolds was convicted and sentenced to imprisonment at hard labor and a fine.

• The indictment was invalid because the grand jury was composed of only fifteen members, contrary to federal law (Rev. Stat. § 808) requiring at least sixteen for federal courts.
• The trial court improperly overruled his challenges for cause against petit jurors who admitted to having formed an opinion on his guilt.
• The trial court improperly sustained the government's challenges for cause against jurors who practiced polygamy.
• The admission of Amelia Jane Schofield's prior testimony violated his Sixth Amendment right to confront witnesses, as an insufficient foundation was laid to prove her unavailability was due to his procurement.
• The federal anti-bigamy law (Rev. Stat. § 5352) was unconstitutional as applied to him because it infringed upon his First Amendment right to the free exercise of religion, as polygamy was a part of his religious duty.
• The trial court's jury instruction regarding the societal consequences of polygamy was improper and prejudicial.
• The sentence to "hard labor" was unlawful as the statute only authorized "imprisonment" (raised on rehearing).

• The grand jury of fifteen persons was proper under Utah territorial law, which governed territorial courts, as Rev. Stat. § 808 applied only to U.S. Circuit and District courts.
• The trial court correctly handled jury challenges, as jurors with opinions could still be impartial, and those practicing polygamy were inherently biased.
• Amelia Jane Schofield's prior testimony was admissible because Reynolds procured her absence, thereby forfeiting his confrontation right.
• The First Amendment protects religious belief, not conduct that violates criminal law; the anti-bigamy statute was a valid exercise of congressional power to regulate conduct in the territories for social order.
• The court's jury instructions were proper and did not prejudice the petitioner.

• Whether a grand jury of fifteen persons, as permitted by Utah territorial law, could validly indict for a federal offense in a territorial court.
• Whether the trial court erred in its rulings on challenges to petit jurors based on pre-formed opinions or the practice of polygamy.
• Whether the prior testimony of an absent witness was admissible when evidence suggested the accused procured her absence.
• Whether the federal anti-bigamy statute violated the First Amendment's Free Exercise Clause when applied to an individual whose religion mandated polygamy.
• Whether the trial court's jury instruction on the consequences of polygamy was erroneous.
• Whether a sentence including "hard labor" was lawful under a statute authorizing only "imprisonment."

• The indictment by a fifteen-person grand jury was valid because territorial courts are governed by territorial laws regarding grand jury composition unless Congress specifies otherwise for them; Rev. Stat. § 808 applied only to U.S. Circuit and District Courts.
• The trial court did not err in its rulings on juror challenges; a juror's pre-formed opinion is not automatically disqualifying if they can remain impartial, and jurors practicing polygamy were properly excluded for bias.
• The admission of Amelia Jane Schofield's prior testimony was proper because evidence indicated Reynolds was instrumental in her absence, thus forfeiting his Sixth Amendment right to confrontation for that witness.
• The federal anti-bigamy statute is constitutional and does not violate the Free Exercise Clause; while Congress cannot legislate against mere religious belief, it can prohibit actions that are contrary to social duties or good order, such as polygamy, regardless of religious motivation.
• The trial court's charge to the jury regarding the consequences of polygamy was not improper as it called attention to the nature of the crime and the jury's duty without appealing to passion or prejudice.
• On rehearing, the sentence to "hard labor" was deemed erroneous as the statute prescribed only "imprisonment"; the case was remanded for correction of the sentence.

• Free Exercise Clause (First Amendment) — Defines the constitutional protection of religious freedom. The Court established the belief-action distinction, holding that the clause provides absolute protection for religious beliefs but does not protect religiously motivated actions that violate valid, neutral laws of general applicability aimed at public order and social welfare. Polygamy was classified as such an unprotected action.
• Confrontation Clause (Sixth Amendment) — Guarantees an accused the right to confront witnesses against them. The Court affirmed that this right can be forfeited by the accused's own wrongdoing, such as procuring a witness's absence, allowing prior testimony to be admitted.
• Legislative Power over Territories (Article IV, Section 3, Clause 2) — Confirms Congress's broad power to make rules and regulations for U.S. territories. The anti-bigamy law was upheld as a valid exercise of this power. Territorial courts are legislative courts, distinct from Article III constitutional courts, and their procedures can be regulated by territorial legislatures subject to Congressional oversight.
• Jury Impartiality (Sixth Amendment) — Mandates trial by an impartial jury. The Court held that a juror's formation of an opinion does not automatically constitute partiality if the juror can set aside the opinion and decide the case based on the evidence. The trial court's determination of impartiality is given deference.
• Criminal Intent (Mens Rea) — A general element of crime. The Court held that knowingly committing a prohibited act (bigamy) constitutes the requisite criminal intent, and ignorance or disapproval of the law, even based on religious belief, is not a defense.
• Maxim: "No one shall be permitted to take advantage of his own wrong." — This principle supported the admission of prior testimony of a witness kept away by the accused. Reynolds could not claim a violation of his confrontation rights when he was responsible for the witness's absence.

• "Laws are made for the government of actions, and while they cannot interfere with mere religious belief and opinions, they may with practices."
• "To permit this would be to make the professed doctrines of religious belief superior to the law of the land, and in effect to permit every citizen to become a law unto himself. Government could exist only in name under such circumstances."
• "Congress was deprived of all legislative power over mere opinion, but was left free to reach actions which were in violation of social duties or subversive of good order."
• "Believing with you that religion is a matter which lies solely between man and his God; that he owes account to none other for his faith or his worship; that the legislative powers of the 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 and State." (Quoting Thomas Jefferson).

• American Insurance Co. v. Canter, 1 Pet. 511 — Referenced to establish that territorial courts are legislative courts, not constitutional courts under Article III, allowing for different procedural rules (like grand jury size) as determined by territorial law or Congress.
• Clinton v. Englebrecht, 13 Wall. 434 — Supported the view that territorial laws govern the impaneling of juries in territorial courts unless Congress explicitly provides otherwise.
• Burr's Trial (1 Burr's Trial, 416) — Chief Justice Marshall's standard for juror impartiality was invoked: light impressions that leave the mind open are not disqualifying, unlike strong impressions that close the mind to evidence.
• Lord Morley's Case (6 State Trials, 770) — An early English authority cited for the principle that if a witness is detained by the procurement of the prisoner, the witness's prior examination may be read in evidence.
• Regina v. Scaife (17 Ad. & El. N. s. 242) — English case supporting the admission of a witness's deposition if the prisoner contrived to keep the witness away.

• Revised Statutes, Sect. 5352 — The federal statute criminalizing bigamy in U.S. territories, the constitutionality of which was upheld in this case.
• Revised Statutes, Sect. 808 — Stipulates the number of grand jurors for U.S. Circuit and District Courts. The Court held this section did not apply to Utah's territorial courts.
• First Amendment, U.S. Constitution — Its Free Exercise Clause was central to Reynolds' defense. The Court interpreted it to protect belief but not actions violating criminal law.
• Sixth Amendment, U.S. Constitution — Its Confrontation Clause and Impartial Jury Clause were relevant to issues of admitting prior testimony and jury selection.
• Compiled Laws of Utah (1876), p. 357 (Territorial Act of Feb. 18, 1870) — Utah territorial law stipulating a grand jury of fifteen persons, which the Court found applicable.
• Virginia Act for Establishing Religious Freedom — Referenced for its historical significance in distinguishing between religious opinion (protected) and overt acts against peace and good order (subject to government regulation).

• Mr. Justice Field — Justice Field concurred with the majority on most points but dissented regarding the admission of Amelia Jane Schofield's testimony from a former trial. He argued that an insufficient evidentiary foundation was laid to prove that Reynolds had procured her absence, and that the authorities cited by the majority did not support the admission of her testimony under the circumstances presented.