The relationship between trauma and the development of Parkinson's disease has been an issue in neurology since James Parkinson's initial 1817 essay. This paper will delineate the historical development of the concept of trauma as an etiologic agent in Parkinson's disease and parkinsonism. The strong influence of socioeconomic societal forces in the 1870s with regard to liability laws and the subsequent acceptance in the medical community of the role of peripheral trauma in producing Parkinson's disease is presented. We will also review present-day criteria for assigning head trauma an etiologic role in parkinsonism. The discussion will stress current knowledge regarding trauma and parkinsonism, and it will also review the issues of the possible role of the current litigious society's influence on determining a role for trauma in Parkinson's disease.