Since Brazil's abandonment of dictatorship and return to electoral democracy in the 1980s, expanding the penal arm of the state has functioned as a key legitimizing strategy for politicians, ushering in an unprecedented incarceration boom. Reaching a rate of 325 per 100,000 inhabitants, the inmate population has increased eight-fold, jumping from 88,000 in 1988 to 689,000 in 2018—the largest in Latin America and third largest in the world (surpassed only by the U.S. and China). However, research has yet to examine how court actors manage those who are thrown behind bars, and we therefore lack an understanding of one of the most influential segments of the penal process in defining criminality. As Brazil's jails and prisons confine more individuals than ever before, the country's legal institutions and procedures have simultaneously undergone the deepest transformation in two centuries, influenced by concerns of "due process" and accountability. Not only do reforms signal a pivotal re-organization in the relations of power among existing legal authorities, but they have also spawned the development of a new and central court actor: the public defender. This new legal profession is the first in the history of the country exclusively oriented toward defending the poor, who have long lacked any effective means to defend themselves from accusations and abuse by the police, prosecutors and judges. My dissertation asks: (1) Who are the attorneys who work within this new legal profession? (2) What is the relationship of public defenders to their clients and other court actors? (3) What does the work of public defenders look like at the ground level? This study is a two-site ethnography of public defenders in the Brazilian cities of Salvador, Bahia and São Paulo, São Paulo. I will conduct semi-structured in-depth interviews with public defenders in each city, as well as conduct participant observation of the daily activities of public defenders who more specifically work within criminal drug courts as a window into the pr