They have done so not by enforcing previously existing legislation but by crafting their own executive orders, styling those orders as if they were laws, using state and local police to enforce those so-called laws and — presumably when life returns to normal and the courts reopen — prosecuting the alleged offenders in court.
It is hard to believe that any judge in America would permit a criminal trial of any person for violating a standard of behavior that has not been enacted into law by a legislature. We know this because under our system of representative government, separated powers and guaranteed liberties, only the legislative branch can craft laws and assign punishments for noncompliance. This is Constitutional Law 101. Supreme Court Justice Neil Gorsuch has written that the executive branch cannot enforce a law that it has written. If it does, we will have approached tyranny.
Have we approached tyranny already?