Long before Oklahoma became a state in 1907, cattle rustlers, horse thieves, and other criminals saw the land as a place to exploit resources and evade capture. But in the heyday of the outlaw era after the Civil War, Indigenous police officers-mounted Cherokee, Choctaw, Chickasaw, Muscogee, and Seminole Lighthorse units-brought them to justice. In The Lighthorse Police, Donald L. Fixico weaves a lively history of these Five Tribes' law enforcement organizations as he explores their origin, operation, and survival from the late eighteenth century to the present. Fixico begins by delving into the Five Tribes' systems of justice prior to removal to Indian Territory in the 1830s, and their shift from adhering to clan-based law to national laws. He traces the Cherokees' and Choctaws' creation of constitutions and lighthorse units as expressions of tribal sovereignty prior to removal, and the Chickasaws', Muscogees', and Seminoles' development of these after removal. In detailing the decades that followed, he draws on the stories of individual lighthorsemen to paint a compelling portrait of territorial violence and justice. In tandem with his exploration of tribal justice, Fixico investigates "white justice" in the region after the Civil War. This justice was delivered by federal marshals like Fort Smith's infamous "hanging judge," Isaac Parker, and their deputies. Fixico demonstrates how federal and Native officers clashed and ultimately worked together to catch criminals. After statehood, the lighthorse fell into disuse, but the organizations resurged in the 1970s. Today, lighthorse officers drive modern patrol cars to protect their communities. In its exploration of law and order from an Indigenous perspective, The Lighthorse Police tells a broader story about sovereignty and violence, Indigenous justice and white justice, and the camaraderie and pride shared by law enforcers across time.