The creation of legal parameters to structure social relations is a basic feature of modern capitalist society. Law plays a major role in shaping the institutional setting within which conflicts arise, develop, and reach their resolution. Likewise, legislative solutions to pressing social conflicts create new possibilities and strategies for social change. The struggles between capitalists and the working class that have historically marked capitalist economic development constitute a central arena for the legislative restructuring of social relations. Yet, few have systematically studied the role of law in shaping the development of capital-labor relations (for some important exceptions, see Steinberg, 1982; Tomlins, 1985). In this paper, we explore the legal structuring of American working-class militancy in the twentieth century, a prominent dimension of capital-labor relations, but one for which the legislative underpinnings remain unclear.