AILSA CHANG, HOST:
Now to a quarantine that wasn't. President Trump floated and then backed away from the idea of imposing a quarantine on residents of New York, New Jersey and Connecticut last week. That region has been the hardest hit by the coronavirus pandemic. Legal experts say he has no authority to institute such a lockdown, but they say he can curtail air travel, something else he has hinted he might do. NPR's Brian Naylor reports.
BRIAN NAYLOR, BYLINE: In 1878, a yellow fever epidemic spread up the Mississippi Valley from New Orleans. States and towns imposed their own so-called shotgun quarantines with authorities blocking roads and railroads with armed force to keep people fleeing the epidemic from traveling into nonaffected areas. Polly Price is a professor of public health at Emory University.
POLLY PRICE: The early version of the U.S. Public Health Service ended up setting up refugee camps for people who were trying to flee Pensacola and Mobile and New Orleans but couldn't go anywhere because places further north wouldn't let them in. And there were people that could not leave Memphis. Armed guards were set up on the other side of the River in Arkansas.
NAYLOR: As many as 20,000 people died from that epidemic. Congress eventually approved the Public Health Service Act, which gives the secretary of health and human services the power to prevent the entry and spread of communicable diseases from foreign countries into the U.S. and between the states. But Price says it's a limited authority.
PRICE: If you're talking about quarantine in terms of encouraging people to stay home or closing businesses - and that's what public health folks talk about as social distancing measures - really, I think from the White House, that can be advisory only and that those are exclusively state powers.
NAYLOR: Washington Attorney Bradley Moss, who specializes in national security law, agrees. He says that under the concept of federalism...
BRADLEY MOSS: The federal government lacks the ability to impose a national quarantine in this context, unless either Congress were to authorize it or if the states collectively, as a whole, were to join in in agreeing to it. The power to impose these kind of categorical, broad, sweeping quarantines is something that's largely delegated to the states.
NAYLOR: The only exception, Moss says, is the federal Centers for Disease Control and Prevention's authority to keep people known to be carrying communicable diseases from traveling between states.
MOSS: That was designed to be rather particularized and specific and not in the kind of broad, you know, nationwide crackdown or a quarantine that the president had been musing about.
NAYLOR: The president does have tools available to keep people from traveling from state to state, including controlling air travel. Trump spoke on Wednesday of possibly prohibiting flights between cities where there have been large coronavirus outbreaks.
(SOUNDBITE OF ARCHIVED RECORDING)
PRESIDENT DONALD TRUMP: We are thinking about hot spots where you go from spot to spot, both hot. And we'll let you know fairly soon.
NAYLOR: And Price says there is precedent for the government limiting air travel.
PRICE: You'll recall, after 9/11, FAA grounded all air travel in the United States for some time. So there's clearly federal authority for air travel. If that's the sort of quarantine lockdown type thing that we're talking about, there's clearly federal authority there.
NAYLOR: But that's it. The president has no authority to impose a federal quarantine or lockdown, and Trump seems to have backed away from that idea.
Brian Naylor, NPR News.
(SOUNDBITE OF STRFKR SONG, "SATELLITE") Transcript provided by NPR, Copyright NPR.