Legal and ecomic analyses overlap and interact in many areas. Recent U.S. Supreme Court and lower court decisions on class action lawsuits clearly focus on the critical role that ecomic analysis plays in determining the outcome of class actions. Wal-Mart Stores, Inc. v. Dukes and Comcast Corp. v. Behrend have made national headlines, raising the bar in class certification for showing common impact and preponderance through expert testimony. These decisions have turned on the adequacy of the analyses put forth by expert ecomists, finding the analyses of the plaintiffs' ecomists to be insufficient. The decisions will have significant implications for use of expert testifiers in class certification and in estimation of monetary damages, presenting challenges to both attorneys and ecomists in antitrust and other class actions. This book focuses on the changing landscape of class action law and its interaction with the ecomic analysis of key issues in class actions. Articles examine the elements of class action law from diverse viewpoints, featuring defendant and plaintiff perspectives, concerning domestic and international law, and written by lawyers and ecomists.