Earlier quoted context omitted.
> but can't help that They're fining (~$140) and detaining people who don't follow the rules in France. https://translate.google.com/translate?sl=fr&tl=en&u=https%3...
Doing that in the US is a Supreme Court case waiting to happen.
It would logically follow that if the quarantine is legal, penalties for violating it are also legal.
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Most of those cases are quite old, but they're still the ruling precedent on the topic as far as my (limited) knowledge goes.
For one that went to the Supreme Court in 1902 and continues to be cited:
Compagnie Francaise de Navigation a Vapeur v. Louisiana Board of Health
https://en.wikipedia.org/wiki/Compagnie_Francaise_de_Navigat...