In modern society, there is a division of labor between the legal system (the law) and the prison system. The law has been around thousands of years, but the prison system is a few hundred years old. The legal system makes the legal/illegal (or lawful/unlawful) distinction, but it doesn’t carry out the punishment. Beginning in the late 18th century, punishment moved to a private context; it ceased to be a public spectacle. This was about the time that the difference between private and public was established. Executions and corporal punishment were moved behind prison walls because the public spectacle of punishment tended to garner sympathy for the criminal and shame for the justice system.
In other words, penal reform was not motivated by humanitarian values. It was just recognized that public executions and various forms of corporal punishment were not effective means of social control. The focus of discipline shifted from the body to the soul. The same might be said for corporal punishment in the schools. We might assume that corporal punishment in the school fell into disrepute because society has become more humane, but that would be a misreading. It would be more accurate to say that corporal punishment in the schools had too many unintended consequences and made the educational process more difficult.
As for penal reform, Foucault writes.
It was as if the punishment was thought to equal, if not to exceed, in savagery the crime itself, to accustom the spectator to a ferocity from which to divert them, to show them the frequency of the crime, to make the executioner resemble the criminal, judges murderers, to reverse the roles at the last moment, to make the tortured criminal and object or pity or admiration. . . .
Punishment, then, will tend become the most hidden part of the penal process. . . . Now the scandal and the light are to be distributed differently; it is the conviction itself that marks the offender with the unequivocally negative: the publicity has shifted to the trial, and to the sentence; the execution itself is a like an additional shame that justice is ashamed to impose on the condemned man; to it keeps its distance from the act, tending always to entrust it to others, under the seal of secrecy. . . . Hence the double system of protection that justice has set up between itself and the punishment it imposes. Those who carry out the penalty tend to become an autonomous sector; justice is relieved of the responsibility for it by a bureaucratic concealment of the penalty itself.Foucault, Michel. Discipline and Punish: The Birth of the Prison, 9-10.
The word justice here seems equivalent to what Luhmann calls the legal system. When Foucault describes the process that makes “the executioner resemble the criminal, judges murderers,” he points out the need for functional differentiation. To achieve that differentiation, the punishment process was handed off to a new, different system–the prison system.
As a social system, the prison will find ways to reproduce itself, which means it becomes an end in itself.
Another problem is that the prison system is closely coupled to the economy. Many small towns depend on prisons for employment. We also have the privatization of the prison system, or the prison-industrial complex. This is an obvious corruption of the prison system, much like for-profit schools and hospitals.
Division of labor, or functional differentiation, among the economy, law, education, science, art, politics, etc., is the best way to prevent the concentration of power within a single system. This the premise behind the separation of powers in government. If the prison becomes an end in itself, there must be counteracting systems that more or less hold it in check.
If I want to call the prison system is a social system of modern society, I need to determine what the communication medium is. We might call it discipline–that is, strict rules and regulations that take away a person’s freedom to move about and make his own choices about what he will do every day. The prisoner loses the freedom to determine when he goes to bed and when he wakes up, what time he eats and what he eats, what kind of clothes he wears, etc. The coding might then be regulated/nonregulated, which would mean that not every aspect of a prisoner’s daily life is regulated. A prisoner can still select his own friends, choose to brush his teeth or not, choose to write letters or not, choose to read or not, etc. The taking away of freedoms has replaced the corporal punishment of the premodern era.
The prison system, in this case, would be a global system, but this doesn’t mean it is organized or controlled like a massive organization. The legal system, political system, and all the other function systems are not organizations either. This is why the global political system is not a global government. The only thing required is that the system operates all over the world and makes the same fundamental distinction everywhere. The legal system is a global system because everywhere the primary distinction is legal/illegal.
I’ve argued that journalism is a function system of modern society, rather just being an aspect of the mass media; so the prison system would be one more. However, it would be more accurate to say, “Call the prison system a function system” or “Call journalism a function system.” We are doing something in order to see what follows. We are not saying X is or is not a Y.