To preserve democratic accountability, the actions of federal agencies remain subject to review by elected officials in the legislative and executive branches. Yet given the vast scope and complexity of the modern federal government, elected officials cannot possibly intervene in all agency matters. This leaves the courts to evaluate agency actions. Applying Rosenbloom's separation of powers theory of public administration to Nagel's theory of power as anticipated exchange, we expect that agencies become more judicialized in response to the courts' influence. Leveraging novel data on personnel records, agency litigation, and policymaking from 1996 to 2016, we estimate regression models using ordinary least squares to provide an original and systematic account of the courts’ influence on agency personnel and professionalization. We find that agencies become more judicialized with increased exposure to the courts. Our dynamic comparison of the rise and fall of the number of judge-like policymakers within agencies highlights agency responses to judicial procedural preferences and suggests that federal agencies adopt personnel and processes that respond to the institutional perspectives of all three branches of government.