In a recent political crisis, two Swiss cantonal authorities planned legislation in order to relieve medical professionals of their legal duty to respect prisoners' medical confidentiality. The ensuing debate has demonstrated the vulnerability of medical confidentiality today. In this article, historical data shows that medical secrecy was constantly attacked in the past, that the nature of medical confidentiality evolved through time and that the analysis of relevant negotiations reveals social and cultural values. Our demonstration is based on three moments in history. First, at the end of the 16th century, lay authorities put pressure on physicians to disclose the names of patients suffering from syphilis. Secondly, in the 18th century, physicians faced constant demands for information about patients' health from families and friends, social groups of which the physician himself was often a member. Thirdly, employers and insurance companies in the 20th century requested medical data on sick employees. History helps us understand present day issues. In the case of secrecy, it reveals that medical secrecy is a plastic concept, regularly attacked but also protected by different social actors. Medical secrecy was, and is today, a medical and societal norm that is shaped collectively. Any change in its definition and enforcement was and should be the result of negotiations with all social actors concerned.