Latin. “Power of the county.” The term refers to a group of individuals who may be called upon to help the law enforcement authorities to enforce the law and preserve peace.
“The phrase ‘posse comitatus’ is literally translated from Latin as the ‘power of the county’ and is defined at common law to refer to all those over the age of 15 upon whom a sheriff could call for assistance in preventing any type of civil disorder.” United States v. Hartley, 796 F.2d 112, 114 n.3 (5th Cir. 1986).
“Th[e] authority for calling forth citizens to aid in law enforcement is the posse comitatus power. The posse comitatus power predates the nation’s founding and has a complicated history. At the federal level, the Fugitive Slave Act of 1850 contained posse comitatus provisions enabling federal law enforcement officers to compel northerners to assist in the capture of enslaved people who had escaped bondage. After the Civil War, the power was used in reverse to enforce civil rights legislation in the Reconstruction south. But the more familiar use of the posse comitatus power was the western frontier version: where a sheriff summoned the posse to pursue an escaped outlaw or confront a violent gang. During this era, preservation of the peace did not fall exclusively to peace officers. On the frontier, preserving the peace was public duty.” Gund v. County of Trinity, 20 Cal. Daily Op. Serv. 8995 (Cal. Aug. 27, 2020), citations omitted.