The normed corruption model stems from the Knapp Commission's analysis of police corruption in New York City in the early 1970's and the subsequent elimination of serious systemic corruption in the New York City Police Department. The normed corruption model defines "normed corruption" as officer deviation from ethical behavior for which officers are not generally disciplined by the department. The normed corruption model proposes that administrative discipline shapes police officers' perceptions of the range of normed corruption in an agency. Behavior for which officers are not generally disciplined becomes custom. In agencies where the normed corruption level is high, some criminally corrupt activities become normed. Conversely, as the range of organizationally defined corruption is expanded, the range of normed corruption contracts. Factors that determine the range of normed corruption include the political environment, the ethical quality of police leadership, the quality of recruitment/retention policies, educational requirements for applicants, and the degree to which police unions influence the managerial policies of the department. The key to controlling, if not eliminating, police corruption is the development of strong internal controls that produce a heightened risk of detection for unethical behavior clearly defined by the department, such that there is "zero tolerance" for such behavior. Long-term change depends upon the internalization of these ethical standards as they become embedded values in the police subculture. 1 figure and 19 references