I've read arguments against quarantine for those who have come in contact with the infected and not found them persuasive.
I find the constitutional arguments against quite persuasive.
One could, for example, *test* them. I know it costs money, but we generally require the government to go to great lengths, and expense, before imprisoning people. The only reason for the quarantine is to avoid paying for tests, and to let an-abundance-of-ignorance masquerade as an-abundance-of-caution.
Requiring blood tests every 24-48 hours poses no insurmountable constitutional hurdles and would likely be welcomed by those being tested - Mr. Duncan might be alive today with a testing requirement, but not a quarantine requirement.
It's generally a good idea to require society to try hard before violating civil rights this badly, yet New York and Illinois seem to have put no thought into this at all. Who pays for damages? Is the state prepared to provide as much support to someone imprisoned in their home as they do to a serial killer in the penitentiary?
PS. Does the number 21 actually have any scientific standing?