Frontier Justice looks beyond the lawlessness and violence of frontiers to reveal instead the intricate tapestry of relationships that underpinned the development of civil society there. The book looks at northern Patagonia, which was military annexed to Argentina between 1878 and 1885. The Argentine government sought to develop in the region the kind of practices and institutions that would turn "barbarism" into "civilization." Using court cases to reconstruct the partnerships between prominent neighbors and the police, among neighbors themselves, and between police, judges, and prosecutors, the book argues that settlers were active stakeholders in the establishment and continued functioning of the frontier state.

The book centers an unusual cast of frontier denizens, tackling issues of gender, race, patronage, and colonialism to better understand the competing sources of legitimacy in a newly incorporated area. By the time the national government finally sought to assert its presence more forcefully in the 1930s and 1940s, the population in northern Patagonia had developed its own "pioneer" political culture, built on patronage and informal legal arrangements and reliant on grassroots legitimacy.