Richard Posner's version of judicial self-restraint implies that individual Justices who embrace restraint would tend to uphold the constitutionality of a law even if it went against their preferences or ideology. Judge Posner suggests that this form of restraint once existed but no longer does. Using a dataset of cases that considered the constitutionality of federal laws, we explore whether, in line with Judge Posner's hypothesis, the Court grew more activist (that is, more willing to strike laws) over the period between 1937 and 2009 and whether the ideological leanings of Justices, and not judicial self-restraint, better explain how they voted in cases challenging the constitutionality of federal laws. Our results answer the question we pose in the Essay's title in the affirmative: there was such a thing as judicial self-restraint, but there no longer is, just as Judge Posner suggests. Justices appointed since the 1960s were and remain ideological in their approach to the constitutionality of federal laws.