Foucault dates the completion of the carceral system to February 22, 1840: the date of the opening of Mettray prison colony. This colony is the disciplinary form at its most extreme. The chiefs and deputies at Mettray were technicians of behavior. Their task was to produce bodies that were docile and capable. Historians of the human sciences also date the birth of scientific psychology to this time. Mettray represented the birth of a new kind of supervision.
Why choose this moment as the beginning of the modern art of punishment? Mettray was the most famous of a series of carceral institutions. If the great classical form of confinement was dismantled, it still existed albeit in a different way. A carceral continuum was constructed that included confinement, judicial punishment and institutions of discipline. The breadth and precocity of this phenomenon was striking. Prison turned the punitive procedure into a penitentiary technique, with several important results: One) a slow continuous gradation was established that made it possible to move from order to offense and back to the "norm". Two) the carceral network allows the recruitment of major delinquents—the nineteenth century created channels within the system that created docility and delinquency together. Three) most importantly, the carceral succeeds in making the power to punish legitimate and accepted. The theory of the contract only partly explains the rise of a new power to punish; another answer comes from the idea of a carceral continuum that was the technical counterpart to granting a right to punish. Four) the carceral allowed the emergence of a new form of law: the norm. Now, the judges of normality were everywhere; a reign of the normative exists, to which everyone subjects his body. Five) the carceral texture of society allows the body to be captured and observed. Six) because the prison was rooted in the mechanisms and strategies of power, it could resist attempts to abolish it. This does not mean that it cannot be altered: processes that affect its utility, and the growth of other supervisory networks, such as medicine, psychiatry and social work, will alter the prison. The overall political issue of prisons is whether we should have them, or something else. Now the problem lies in the increasing use of mechanisms of normalization and the powers attached to them. The carceral city is very different to the theater of punishment. Laws and courts do not control the prison, but vice versa. The prison is linked to a carceral network that normalizes. Ultimately only the rules of strategy control these mechanisms. Foucault sees this book as a historical background to various studies of power, normalization and the formation of knowledge in society.
This section draws together the threads of Foucault's argument, with few new ideas. The prison, the penitentiary and the carceral system are all put in their place. The carceral system in particular is extended beyond the walls of the prison; we can, Foucault suggests, talk about the modern system of punishment as a "carceral city" because the prison is so closely linked to the rest of society by a network of power that shapes everyone's life.
A new way of seeing the carceral system is also suggested. The idea of a continuum, in which different levels of severity are arranged on a scale, resembles the kind of classification or ranking that is established in the process of observation. An acceptance of the carceral system points to the triumph of the law of the norm, and to the end of Foucault's account of the transformation of judgment. A society like ours where the carceral system operates is one in which the human sciences judge all and exclude some on the basis of norms. This is an unchangeable fact, but it should not prevent resistance against the rule of the norm.
The carceral system is powerful and in many ways harmful, but Foucault holds out some hope of change. However, the chief agent of change is likely to be the growth of the human sciences themselves, which may one day take over some of the supervisory and observational work of the prison. Whether this will represent a degree of progress is left uncertain. Foucault's last words suggest the real purpose of this account is not to inspire rebellion against the modern disciplinary system, but to promote understanding of its components and operation.