This book examines labour regulation and labour mobility in two professional baseball leagues: Major League Baseball (MLB) in the United States and Nippon Professional Baseball (NPB) in Japan. Through vivid comparative study, Matt Nichol explores how each league internally regulates labour mobility and how this internal regulation engages with external regulation from the legislature, statutory authorities and the courts. This comparison of two highly restrictive labour markets utilizes regulatory theory and labour regulation and suggests a framework for a global player transfer system in baseball. Each system of labour regulation can be viewed as an autopoietic system of law that utilizes voluntary self-regulation as the basis for regulation. While the regulatory systems in each league govern labour mobility in a similar manner using labour controls such as the draft, the reserve system and free agency, the two systems operate differently in terms of the level of labour mobility enjoyed by players. Formal rules, informal rules and normative practice result in MLB having relatively high levels of labour mobility for free agent players while similar players enjoy limited mobility in NPB. The book's engaging, multifaceted focus and comparative nature make it an excellent resource for lawyers, academics and advanced students interested in labour law, sports law, and Asian and European law.