The Nauvoo Expositor was a newspaper in Nauvoo, Illinois that published only one issue, which was dated June 7, 1844. The Expositor was founded by several disaffected associates of Joseph Smith, Jr., some of whom claimed that Smith had attempted to seduce their wives in the name of plural marriage.

The bulk of the Expositor's single issue was devoted to criticism of Smith, founder of the Latter Day Saint movement and the mayor of Nauvoo. After two days of consultation, Smith and the Nauvoo city council voted on June 10, 1844 to declare the paper a public nuisance, and ordered the paper's printing press destroyed.  The town marshal carried out the order that evening.  These actions generated considerable disturbance, and culminated in Smith's assassination by a vigilante group while he was in legal custody and awaiting a trial in nearby Carthage.

The paper's criticism of Smith was focused on three main points: (1) the opinion that Smith had once been a true prophet, but had become a fallen prophet because of his introduction of plural marriage, exaltation and other controversial doctrines; (2) the opinion that as church president and Nauvoo mayor, Smith held too much power and desired to create a theocracy; and (3) the belief that Smith was corrupting young women by forcing, coercing or introducing them to the practice of plural marriage.

Nauvoo's charter granted the city council powers equal to the Illinois legislature within the jurisdiction of Nauvoo. Power was granted to the city council to pass ordinances for the order and welfare of the city. For two days, Smith and the city council debated and discussed the matter. Ultimately, after considering William Blackstone's canon, the council declared the press a nuisance and ordered Smith, as Nauvoo's mayor, to order the city marshall to destroy the paper and the press.

Critics regarded the press's destruction as an ethical affront to the freedom of the press. However, since the events there has been much discussion as to whether the council's actions were legal insofar as the law would have been contemporarily understood. In any event, whether or not the council's actions were strictly legal, there is general agreement among historians that the press's destruction escalated the continuing conflict between the Mormon community and their critics, leading ultimately to Smith's assassination.

The Expositor was published by William Law and six associates. Law had been a former member of the First Presidency and a close associate to Smith. During the course of his association with Smith, Law came to believe that Smith had made several proposals to Law's wife Jane, under the premise that Jane Law would enter a polygamous marriage with Smith.  Law claimed that when he confronted his wife, she told him that Smith had "asked her to give him half her love; she was at liberty to keep the other half for her husband." Some historians have also concluded that Smith had also planned to ask Smith's own wife, Emma, to enter a similar polygamous relationship with William Law,[citation needed] but was directed by revelation not to follow through.  As a result of what William Law came to believe about Joseph Smith, Law became disaffected with Smith and left the church. The Expositor was planned as an exposé of the church's practices which Law opposed.

The Expositor was declared a nuisance in part because it was deemed that if it were not immediately checked, it would inflame either Nauvoo's Mormon citizens or non-Mormon mobs and lead to public disorder or violence such as the Mormons had experienced during the Mormon War in Missouri.[citation needed] In a letter to Governor Thomas Ford written four days after the destruction of the press, Smith described the city council’s opinion of the paper and its authors:

In the investigation it appeared evident to the council that the proprietors were a set of unprincipled men, lawless, debouchees, counterfeiters, Bogus Makers, gamblers, peace disturbers, and that the grand object of said proprietors was to destroy our constitutional rights and chartered privileges; to overthrow all good and wholesome regulations in society; to strengthen themselves against the municipality; to fortify themselves against the church of which I am a member, and destroy all our religious rights and privileges, by libels, slanders, falsehoods, perjury & sticking at no corruption to accomplish their hellish purposes. and that said paper of itself was libelous of the deepest dye, and very injurious as a vehicle of defamation,—tending to corrupt the morals, and disturb the peace, tranquillity and happiness of the whole community, and especially that of Nauvoo.

Assuming that the mayor's declaration and order passed the ex post facto legal hurdle, it also needed to meet the Nauvoo Charter's requirement that new ordinances must be published under certain criteria and could only become effective 30 days after the ordinance was passed. This requirement was not met.

This brick building was located on Mulholland Street on the block east of the Nauvoo Temple. On the second floor of this building was located the printing press on which the Nauvoo Expositor was printed. The destruction of the press was the event which triggered a series of events culminating in the murder of Joseph and Hyrum Smith at Carthage 20 days after its publication.

Early in 1843 a group of members of the Church at Nauvoo, including Joseph Smith's second counselor and one of the presidents of the Nauvoo Stake and several business and professional people, commenced opposing Joseph Smith because of new doctrine and practices which were introduced in the Church. Foremost among these so-called objectionable tenets were the practice of plural marriage, eternal progression of man toward godhood, eternalizing of the marriage covenant, the endowment ceremony, and the political kingdom of God

The Expositor Office

with its secret Council of Fifty. After these men were excommunicated from the Church in April 1844, they purchased a press and published a paper entitled the Nauvoo Expositor, the only issue appearing June 7. This first and last edition of the paper declared that Joseph Smith had become a tyrant, ruling Nauvoo contrary to American principles of separation of church and state; that he had introduced into the Church doctrine and practices which were contrary to the original teachings of the Church, particularly that secretly he was practicing plural marriage which they termed "whoredoms and abominations." They announced their intention to seek the repeal of the Nauvoo Charter so that Nauvoo might become a city governed by American standards of democracy.

The Expositor appeared on Friday afternoon, and the following morning and the Monday thereafter the city council met to consider its threat to the peace and security of the city. With the powers granted by the city charter, they declared the newspaper a nuisance, as they felt its declarations threatened the security of the city. They authorized the mayor (Joseph Smith) to see that the nuisance was abated. The Prophet instructed the city marshal to abate the nuisance which he and his men accomplished by breaking into the printing shop, throwing the press into street where it was smashed with a sledge hammer, dumping the type into the street, and burning the undistributed copies of the newspaper. Such an extralegal method of abating a newspaper was not without precedent in Illinois (though not in keeping with long established practices concerning abatement of a public press), but it was viewed as a violation to the federal Constitution which forbids destruction of property without due process of law. The city council had only the authority to abate the nuisance by suspending further publication of the paper pending a court hearing which would determine whether it was a public nuisance.

The proprietor of the paper went to Carthage and swore out a warrant for the 18 members of the city council, charging that they had violated the federal Constitution by destroying property with the resultant implication of "suppression of the freedom of the press." In response to the charge 15 members of the Nauvoo city council appeared before the justice of the peace in Carthage on Tuesday, June 25, and were bound over to the next term of the circuit court on bail of $500 each. Jointly they posted $7500 in bonds and some of them returned to Nauvoo that afternoon. Joseph and Hyrum, however, remained in Carthage to have an interview with Governor Ford. While awaiting audience with him, they were arrested on charges of treason and rioting for having used some of the Nauvoo Legion to assist the town marshal in the destruction of Expositor equipment. For this charge they were committed to the Carthage jail that afternoon.