This Article offers a new interpretation of the founding of the Department of Justice (DOJ) in 1870 as an effort to shrink and professionalize the federal government. The traditional view is that Congress created the DOJ to increase the federal government’s capacity to litigate a growing docket due to the Civil War. More recent scholarship contends that Congress created the DOJ to enforce Reconstruction and ex-slaves’ civil rights. However, it has been overlooked that the DOJ Act eliminated about one-third of federal legal staff. The founding of the DOJ had less to do with Reconstruction, and more to do with “retrenchment” (budget cutting and anti-patronage reform). The DOJ’s creation was linked with major professionalization efforts, such as the founding of modern bar associations, to make the practice of law more exclusive and more independent from partisan politics. In this new interpretation, the DOJ’s creation runs in the opposite direction from one historical trend, the growth of the federal government’s size. Instead, it was at the very leading edge of two other major trends: the professionalization of American lawyers and the rise of bureaucratic autonomy and expertise. This story helps explain a historical paradox: how the uniquely American system of formal presidential control over prosecution evolved alongside the norms and structures of professional independence.