Politics that didn't Happen

In 2016, the FBI was on a roll. Not content to take Apple and WhatsApp to court over encryption, although most tech experts agreed that it was a rather stupid idea, they also felt that school were, most definitely, a dangerous place for "freedom" (how exactly they define that word is unknown as of yet, seemingly varying from PR-release to PR-release). Indeed, the bureau feared that schools might become hotbeds of "terrorism" (same as "freedom"). Luckily for the american people, they came up with a solution.
Students (and teachers) expressing strong political opinions, criticising western governments or values, doubting capitalism, or defying current social norms, were "at risk", and should be reported to the relevant authorities.
Wether it was because of the flashy presidential campaign, or because after 9/11, americans had gained the reflex of nodding their head as soon as somebody used the word "terrorism" as a reason to do something, the FBI's new plan was put into place without much opposition. However, things did not turn out quite as expected.
Teenagers who were growing tired of swatting welcomed the new challenge, and, in the first school year after the implementation of their plan, the FBI received over a hundred thousand reports of abnormal behavior by students. As it turned out, most of those were false-flag operations by students against students, and such a strain on ressources that it seemd the FBI would be paralyzed if it did not suspend the program.
The bureau, however, did not back down, and decided that, instead of time-consuming investigations into the validity of accusations, it would simply consider that people who were reported to them had to have done something, and gave everybody a preventive jail sentence of at least six months.
Ten years later, the population of the U.S.A. shrunk from 300 to 100 million, mainly due to mass emigration. Of the remaining people, 10% are in the FBI, and 30% are in jail. But hey, no major terrorist attacks! (probably...)