This paper examines the 'Blue Code of Silence' and its contribution to police corruption. After offering evidence for the existence of such a code, the paper locates the origins of the code in the work and culture of policing. The paper also examines cases, commission reports and an original case study to understand how the code is reinforced. Based on 'participant observation' research of the New York County Prosecutor's Official Corruption Unit, the paper also illustrates how the code impedes investigations by police overseers. Finally, the paper discusses various measures to address the code of silence.