Citizens for Constitutional Freedom (C4CF), later also known as People for Constitutional Freedom (P4CF), was the name taken on January 4, 2016, by an armed private U.S. militia that occupied the U.S. Fish and Wildlife Service's Malheur National Wildlife Refuge headquarters in the U.S. state of Oregon from January 2 to February 11, 2016. The leader of the organization was Ammon Bundy, son of Cliven D. Bundy, who engaged in a standoff with the federal government over grazing rights on federal land.