James Willis Nesmith was an American politician and lawyer from Oregon. Born in New Brunswick to American parents, he grew up in New Hampshire and Maine. A Democrat, he moved to Oregon Country in 1843 where he entered politics as a judge, a legislator in the Provisional Government of Oregon, a United States Marshal, and after statehood a United States senator and Representative.

The Provisional Government of Oregon was a popularly elected settler government created in the Oregon Country, in the Pacific Northwest region of North America. Its formation had been advanced at the Champoeg Meetings since February 17, 1841, and it existed from May 2, 1843 until March 3, 1849, and provided a legal system and a common defense amongst the mostly American pioneers settling an area then inhabited by the many Indigenous Nations. Much of the region's geography and many of the Natives were not known by people of European descent until several exploratory tours were authorized at the turn of the 18th and 19th centuries. The Organic Laws of Oregon were adopted in 1843 with its preamble stating that settlers only agreed to the laws "until such time as the United States of America extend their jurisdiction over us". According to a message from the government in 1844, the rising settler population was beginning to flourish among the "savages", who were "the chief obstruction to the entrance of civilization" in a land of "ignorance and idolatry".