The Supreme Court got it right the first time (in a Civil War case): The only justification for holding a person without trial is in a battlefield situation (when/where “the civil courts cannot operate”,) or when the individual legally satisfies the criteria for a prisoner of war.
“The only justification for holding a person without trial is in a battlefield situation”
That’s easy, just declare a rebellious county a “battlefield”, and you can “preventively Detain” anyone you want to.