There's a thing called "chilling effects". People stop talking about "risky" subjects because they know they can get prosecuted arbitrarily for it.
The gameplan is simple:
* Someone says something the government doesn't like.
* A plan is devised to get this person in jail and/or to discredit them and/or to ruin their careers.
* In the case of jail, evidence for a crime is collected (from SIGINT) extralegally, and is used to innocuously find, or let someone else find, admissible evidence for the crime. This is called parallel construction and it is very real.
* Maybe they're only sued with the purpose of discrediting them via the press, while making them unable to keep their jobs. Maybe they're actually put in a cage.
It's not out in the open, but it has similar effects to totalitarianism, especially on the part of the population that is more observant and able to affect policy change.
It's not the same, but lets not pretend the US is a lighting beacon of freedom and democracy. Maybe compared to China, but definitely not when compared to e.g. the Netherlands. (I'm biased though.)