“What does the LAW say on cases like this.”
I think the law says an American can’t be incarcerated without due process. At least that’s what some lawyer talking head said. Then you’d have to decide what constitutes “due process” in cases like this.
I could see a case being made for posing a public threat and jailed until otherwise. People refusing to be tested may be an issue. And I can see where people would avoid hospitals and docs if it might result in any know of quaratine (with some thus presenting in dire condition and putting a greater strain on the heath system then).