This essay examines the intellectual history of the idea of judicial restraint, starting with the early debates among the US Constitution’s founding generation. In the late nineteenth century, law professor James Bradley Thayer championed the concept and passed it on to his students and others, including Oliver Wendell Holmes Jr., Learned Hand, Louis Brandeis, and Felix Frankfurter, who modified and applied it based on the jurisprudential preoccupations of a different era. In a masterful account, Brad Snyder examines Justice Frankfurter’s attempt to put the idea into practice. Although Frankfurter arguably made a mess of it, he passed the idea of judicial restraint on to Alexander Bickel and others. Today it remains a topic of much academic debate, while Supreme Court Justices occasionally give the idea lip service when it advances outcomes they desire. I propose that the intellectual history of judicial restraint reflects the all-too-human inability to refrain from exercising power. The founders, focused on the need to mitigate the flaws of human nature in designing the executive and legislative branches, failed to sufficiently foresee how the same flaws would affect members of the judiciary. The failed idea of judicial restraint stands as the legacy of the founders’ mistake.