>It's also not clear if any of this is politically viable. The US is politically farther right compared to Europe and some other countries. Is a more liberal "European style" justice system palatable to US voters?
Are we living in the same country? What's "politically viable" varies massively from place to place.
While there are definitely "tough on crime" districts many major cities elect DAs and elect/appoint judges specifically because they make campaign promises to not be tough on certain classes of crime, recommend community service and treatment instead of jail, etc, etc. These are generally not the cities who's cops you see embroiled in excessive force controversies but they are by no means free of problems with their police forces use of violence.
Overall, the US is entirely to the right of many other places. So even the more liberal places are still "tough on crime". I'm not sure comprehensive reforms will be accepted even in moderate places.
> What's "politically viable" varies massively from place to place.
That's exactly my point. So having any kind of national or federal reform is impossible because Americans cannot agree on anything. Reform from the federal system is needed but any kind of sweeping reform at a nationwide level is impossible.