This Article offers a new explanation for the puzzling origin of modern civil liberties law. Legal scholars have long sought to explain how Progressive lawyers and intellectuals skeptical of individual rights and committed to a strong, activist state came to advocate for robust First Amendment protections after World War I. Most attempts to solve this puzzle focus on the executive branch’s suppression of dissent during World War I and the Red Scare. Once Progressives realized that a powerful administrative state risked stifling debate and deliberation within civil society, the story goes, they turned to civil liberties law in order to limit the reach of that state. Drawing on a wealth of unexplored archival material, this Article inverts the conventional story: It argues that lawyers within the executive branch took the lead in forging a new civil-libertarian consensus and that they did so to strengthen rather than circumscribe the administrative state. Tasked with implementing the World War I draft, Felix Frankfurter, Harlan Fiske Stone, and other War Department administrators embraced civil libertarianism as a tool of state-building, not a trump against state power.