The work creates a link between the perspectives of a given historical social milieu in France and the choices French society made (and makes) about how to conduct judicial and penal activities. Foucault makes the argument how in feudal France, judicial proceedings were largely closed to the public, and the execution of sentence was the opposite. Punishment was all about the spectacle. As French society morphed to more democratic morays, the opposite happened. In contemporary France trials are open to the public, and sentences are largely away from the public gaze.
The author asserts much of the shift is a function of accountability and power. Public display of brutal executions helped keep others in check, at least so the theory goes. Yet crime still happened so one could question the effectiveness of public executions. Foucault points to a balancing act by despots to allow enough public spectacle to instill fear without going so far as to seem unfair, inspiring general insurrection. In the days of kingship, the people were accountable to power. In more modern democratic societies, leadership is more accountable to the people. Many argue if this is really true, but Foucault makes the point of the technology of evermore specific legal codes which in many ways proscribe judges from arbitrariness.
A key point Michel Foucault makes is how punishment has shifted from the specific punishment to fit the crime, to generic punishment for any crime. For example, in feudal France, it would be common for a thief to have his hand(s) cut off. Today, all go to some form of prison and the only variation is the length of stay. The one modern exception to prison sentences is use of the death penalty, yet there are many legal ways to make actual execution a reality for most convicts. Likewise, all forms of execution are the same, not varied based on the specifics of the crime.
On last point I’ll share relates to the intent of punishment. In early France, motive was not considered. Crime x received punishment y. Punishment was to the body with the hopes of creating repentance within the assumed criminal. Because the spectacle was as much for the observers as for the convicted, it was not unusual for penalties to continue post-mortem. For example, a person may be strangled unto death, then disemboweled, drawn and quartered, and body parts put on public display. In such an example, the prisoner is dead after step one yet the punishment went on. Pre-execution torture was intended to extract a confession, but Foucault notes how it was understood such confessions could be false, so other forms of evidence were required for conviction. Confession would not lessen the punishment as it was only one form of evidence, and was more intended to help the sinner repent than it was for proof of culpability.
In modern times, intent or sanity are important parts of sentencing. Just as the old way was to help reform the sinner in the next life, in modern times we look to help heal the soul in this life. In this way we have adopted sentences that involve confinement in mental institutions for example. Foucault sees psychiatric efforts to confirm the accused mental state at the time of the crime, or their ability to stand trial as modern-day technologies of the court system.
The final section of the book focuses on the technology of a panoptic physical prison and the psychological effects such an experiment had on prisoners. I wrote a blog post early about panopticism. Here is the link:
http://bhaven.org/blog/the-modern-virtual-global-panopticon
One final comment. Michel Foucault links many of the disciplinary processes and attitudes used in the penal system with those used in hospitals, the military, and schools. Each of these have a need for regimentation and hierarchy on a large scale. All claim their effort to be for the public good.