Prison and police form a twin mechanism; together they assure in the whole field of illegalities the differentiation, isolation, and use of delinquency. In the illegalities, the police-prison system segments a manipulable delinquency. This delinquency, with specificity, is the result of the system; but it also becomes a part and an instrument of it. So that one should speak of an ensemble of whose three terms (police-prison-delinquency) support one another and form a circuit that is never interrupted. Police surveillance provides the prison with offenders, which the prison transforms into delinquents, the targets and auxiliaries of police supervisions, which regularly send back a certain number of them to prison. And far from being mere administrative bodies that enforce the law, kept the peace and served the public, police departments are policy-making agencies that help to decide which laws are enforced, whose peace is kept, and which public is served.