Normally this authority rests with state governors.Such authority has far-reaching implications for those not yet infected. They are being forcefully detained in an area where infected persons remain.
The last known time that a cordon sanitaire was used was with towns in Zaire during the Ebola outbreak.
The government attempts to balance the good of the community with individual liberty. In times of international crisis, there is a heightened need to zealously protect those individual rights.