The Revolution of 1830 overthrew the Bourbon king Charles X and put the Orléanist Louis-Philippe on the throne. Tocqueville reluctantly took a loyalty oath to keep his job. This placed him in a difficult position with his pro-Bourbon family and relatives, who thought his actions treasonous. But his oath did nothing to allay the regime's mistrust of him. This suspicion was not unwarranted; in 1832 some of Tocqueville's relatives would be involved in a plot to overthrow Louis-Philippe. Beaumont fell under suspicion for similar reasons. He and Tocqueville therefore sought a pretext to leave the country for a while.
Fortunately for them, a shift was taking place, not only in politics but also in penal practices: torture and public executions were being replaced by efforts to rehabilitate criminals. The United States was seen as a vast social laboratory, in which prison experiments were being conducted that might profit France. Tocqueville and Beaumont were therefore able to convince their supervisors to grant them a leave of absence to travel to the United States to study American prisons.It's interesting that was his reason for coming. The shift to rehabilitation is something we've discussed from time to time; it turned out to be based on theories of psychology that hold no water at all. Sadly, if anyone followed the American model of prisons, they made a detour into an expensive new way of failing to solve the problem.
They're subject to an additional complaint, which is that they were probably worse forms of torture than the ones they replaced. Prisoners were forced to remain silent twenty-four hours a day, and kept in solitary confinement when they weren't working in gangs: they were also lashed regularly. The stated point was to "break down their sense of self," so they would be easy to reform. It's roughly the idea later mocked by A Clockwork Orange, but before the advent of psychoactive drugs.
So it turns out that Tocqueville came to learn about something we did poorly but were reputed to do well, and ended up learning about (and writing about) something we did well in fact. That shows a good judgment.