This case book focuses on federal consitutional principles, and specifically focuses on how those principles work.  The introductory comments to each chapter refresh the students' memories of the rules and the reasons the rules were established.  The students are then challenged to evaluate what was done in each case, and analyze whether it was consitutional or not.  These materials are instructive for students of consitutional law and for police who are required to know how to investigate constitutionally.