Posse comitatus
![An American posse in 1922, which captured the outlaws Manuel Martinez and Placidio Silvas, who are in the center of the back row. Martinez and Silvas were arrested for the Ruby Murders after the largest manhunt in the history of the Southwest.[1]](/uploads/202502/03/Ruby_Murders_posse_and_two_prisoners2051.jpg)
Posse comitatus is the common-law or statute law authority of a county sheriff, or other law officer, to conscript any able-bodied man to assist him in keeping the peace or to pursue and arrest a felon, similar to the concept of the "hue and cry." Originally found in English common law, it is generally obsolete; however, it survives in the United States, where it is the law enforcement equivalent of summoning the militia for military purposes.