William Law was an important figure in the early history of the Latter Day Saint movement, holding a position in the church's First Presidency under Joseph Smith Jr. Law was later excommunicated for apostasy from the church and was founder of the short-lived True Church of Jesus Christ of Latter Day Saints. In this capacity, he published a single edition of the Nauvoo Expositor, the destruction of which set in motion a chain of events that eventually led to Smith's death.

The Latter Day Saint movement is the collection of independent church groups that trace their origins to a Christian Restorationist movement founded by Joseph Smith in the late 1820s.