The work examines the legal challenge to the new Bipartisan Campaign Finance Reform Act (BCRA) which is in federal court. Both sides have assembled expert reports and testimony from some of the US's best-known academic experts and political practitioners. These materials, filed with the court but difficult for the general public to access and evaluate, provide a window onto contemporary practices and disputes over party soft money and "issue advocacy". This work contains edited selections of reports filed by scholars and practitioners on both sides of the legal debate over the new campaign finance law. The editors provide an overview of the legal context and empirical issues central to the dispute, as well as roadmaps to each report. The volume does not try to assess the constitutional arguments made in the litigation. Instead, it makes available to the general public and scholars competing arguments and evidence on campaign finance law and practice.