Barry C. Harris and David A. Argue both testified before the FTC/DOJ Hearings on Health Care and Competition Law and Policy on antitrust issues in hospital and physician transactions. Harris, who spoke at a session on hospital geographic market definition, noted that two common mistakes in applying the Merger Guidelines are a failure to identify a market consistent with the stated method of exercising market power and a failure to consider the impact of firms that do not compete throughout the merging firms’ joint service area in assessing the profitability of a hypothetical price increase. One of Argue’s sessions concerned issues in litigating hospital mergers in which he discussed the agencies’ failure to implement the Merger Guidelines framework in their analyses including issues like internal consistency of theories, dynamic analysis, and proper accounting for the Critical Loss. He also addressed aspects of estimating prices in the FTC hospital retrospectives. In addition, Argue discussed issues in physician market definition for antitrust analyses.