I. “Judicial activism” is an expression widely used in popular discourse since its introduction in 1947 in a lay magazine by Arthur Schlesinger Jr., who used the term pejoratively to describe a tendency within the US Supreme Court. Although the phrase acquired currency among public opinion both in America and Europe, its translation into a proper legal concept is no easy task, if at all possible or desirable. Several contributors to this book undertake that task and believe that the concept is intelligible and useful. Notwithstanding the conceptual concerns that run through the volume, the phrase is mostly a pretext for reflection on judicial practice in the European and American contexts, both arguably characterized in these last decades by the introduction of novel normative claims and even policies by judges. That within supposed exercises of practical reason departing from conventional legal method— or legal method as conventionally understood. An understanding of judicial activism around these tenets can be gained from the contributions to this volume. II. There is inevitably a central question deserving the attention of the different contributors, which concerns the degree in which judicial exercises in practical reasoning may amount to forms of judicial usurpation of the legislative function by courts. Moreover, different views as to the nature and scope of legal reasoning lead to different degrees of tolerance regarding what should be admissible to courts. Massimo La Torre, on the one side, and Lawrence Alexander, on the other, find themselves on opposite sides of the spectrum. La Torre, rejecting the platonic noble dream (or nightmare, in his view) of judicial reasoning as a matter of mere acknowledgment or cognition, defends that the main rationale of judicial decisions must be understood as argumentative and interpretative, implying a thorough involvement of the judge in practical reasoning. Contrarily, Alexander looks unfavorably at the exercise of what he names as “first-order practical reason” by judges.