The Work Accidents and Occupational Diseases Act exists in Chile since 1968. It uses a single model for the understanding and management of both somatic diseases like silicosis and psychiatric disorders. During the last decade in Chile, the consultation rates due to psychiatric conditions of probable labor origin has rose over 1,000%, a factor that underscored the deficiencies of this model. The aim of this paper is to analyze the consequences of the application of this act in the psychiatric field for almost 50 years after its promulgation. This article contains an historical overview and an epistemological debate based on the authors’ experience dealing with clinical and administrative work both in occupational psychiatry departments and in regulatory entities. The development of occupational mental health in Chile is examined as part of an historical process that initially did not consider the relationship between work and mental suffering as relevant. The application of a single causality model in psychiatry, as well as the effects of building a psychiatric nosology upon legal rather than medical criteria is contested.