Most quarantine power—that is, the power to restrict the movement of people who might have been exposed to a contagious illness, even if they’re not confirmed to be infected—belongs to states. New York, which is experiencing one of the largest Covid-19 outbreaks in the world, clearly could order a mandatory quarantine of individuals exposed to the coronavirus, for instance.
But the federal government has some quarantine power too—and the limitation of federal rules just to “interstate” spread of disease may be broader than it seems.
These rules have rarely been used, so their boundaries have been little tested in court, possibly resulting in “constitutional conflict that could be too fast-moving for courts to intervene,” wrote Polly Price, an Emory University law and public health professor, in the Atlantic last month.
Public health officials prefer voluntary measures, so the federal rules are as a practical matter “relevant only to air travel” and used mostly for tuberculosis patients, Price noted in 2018 in the Emory Law Journal. But she added that “Congress (and the Supreme Court) envisioned a far greater role for federal intervention in matters of state quarantine than we assume today.”
According to US law, the director of the Centers for Disease Control and Prevention can order quarantined a person who is “reasonably believed” to be infected. But that applies only if that person is crossing state lines—or might infect someone else who would cross into another state, potentially spreading the disease further.
That last clause is likely “pretty easy to satisfy,” wrote Robert Chesney in Lawfare last month.
And “if the federal government determines local efforts are inadequate,” it may be able to step in, according to a 2014 Congressional Research Service report (pdf).
However, the law limits quarantine power to individuals ... says lawyer Bradley Moss on Twitter. A wholesale ban on entering or leaving an affected area is often called a “cordon sanitaire”—but that’s not a legal term in US federal law.