This article analyzes how litigation, court rulings, and legal mobilization have influenced law and policy making related to death from overwork (karōshi) and suicide from overwork (karōjisatsu) in Japan over the course of half a century. It highlights the gradual, but substantial, impact of litigation and court rulings on different levels of governmental measures. By taking a longer-term perspective to assess the political effects of different stages of the judicialization process and focusing on the actors of legal mobilization—particularly, cause lawyers—this study provides a more accurate depiction of the overall process of social and legal changes observed in the recent Japanese labor law reform.