In 1988, hundreds of federal district judges were suddenly confronted with the need to render a decision on the constitutionality of the Sentencing Reform Act and the newly promulgated criminal Sentencing Guidelines. Never before has a question of such importance and involving such significant issues of constitutional law mandated the immediate and simultaneous attention of such a large segment of the federal trial bench. Accordingly, this event provides an archetypal model for exploring the influence of social background, ideology, judicial role and institution, and other factors on judicial decisionmaking. Based upon a unique set of written decisions involving an identical legal problem, the authors have produced an unprecedented empirical study of judicial reasoning in action. By exploiting this treasure trove of data, the authors have looked deeper into the judicial mind and observed the emergence of influences upon the manner in which a judge examined the constitutional issues, adopted a constitutional theory, and engaged in legal reasoning.