U.S. president Martin Van Buren tells Joseph Smith in a personal meeting that the federal government cannot intervene to protect Mormon property or civil rights in Missouri. In 1833 the U.S. Supreme Court had ruled in the Barrow case that the Bill of Rights restrained only the federal government. Until the Civil War and the 14th Amendment the constitutional separation between the federal government and the rights of sovereign states prohibited such intervention. This is also the first meeting between a U.S. president and an LDS president.
[Quinn, D. Michael, The Mormon Hierarchy: Origins of Power, Appendix 7: Selected Chronology of the Church of Jesus Christ of Latter-day Saints, 1830-47, http://amzn.to/origins-power]