Seventeen years after the U.S. Department of Transportation (DOT) granted antitrust immunity (ATI) to an innovative KLM-Northwest joint venture, ATI has become one of the most controversial issues in current aviation law and policy. This article, courtesy of Warren L. Dean, Jr., partner at Thompson Coburn LLP in Washington, D.C. and Jeffrey N. Shane, partner at Hogan & Hartson LLP in Washington, D.C., reviews the history of ATI and its statutory foundation and attempts to place airline alliances in a more contemporary perspective. Criticism of the alliance/ATI development appears to be predicated on a misunderstanding of both the role of alliances as an essential element in the liberalization of international air services and the importance of ATI as a factor in that success.