As of Thursday evening, 11 senators and 59 members of the House had spoken out in favor of a travel ban on flights to and from Ebola-stricken West African nations. But not much attention has been paid to what such a ban would look like, or if it could even reasonably work.

How would a travel ban be implemented?

Practically, the framework already exists for a travel ban, says American University law professor Steve Vladeck. Individuals are already turned away from U.S.-bound flights if they’re deemed a threat or appear on a no-fly list. “A travel ban is just a more wholesale version of that approach — where the U.S. would not allow flights from certain countries to enter U.S. airspace and/or land at U.S. airports,” Vladeck says.

The Federal Aviation Administration, which already gets to decide what planes can enter U.S. airspace and land at American airports, would most likely be in charge of enforcing such a ban, he says.

A ban would be straightforward if the only objective were preventing an Ebola patient from boarding a flight in Monrovia that’s bound for JFK. But in fact, there are few U.S. carriers currently operating direct flights to and from West Africa: Most likely, passengers would arrive stateside after a stopover someplace else. Thomas Duncan, the first patient to be diagnosed with — and die from — Ebola in the U.S., flew from Liberia by way of Brussels.

This is where things get complicated. If the ban is to target all passengers who traveled through West Africa, “that would require a substantial amount of coordination with our friends and partners overseas,” says Vladeck. Countries already share information about air passengers with others — the question is whether the U.S. can convince other countries’ travel ministries to share enough to be able to piece together travelers’ previous stops.

And there remains the question of legality. If the ban is limited to noncitizens, its legality is fairly clear: It’s up to the U.S. to determine its own immigration policy, and it can keep foreign nationals out as it wishes, says Vladeck.

But once we’re talking about a travel ban on American citizens who may be in those areas, “the calculus changes rather dramatically, because courts have generally recognized a right on the part of U.S. citizens to travel,” he says. The question then becomes one of due process: the government would have to make sure the ban allows citizens to demonstrate that they’re not a risk to public health, for example.

What would the external effects of a travel ban be?

Airline stocks have already taken a hit as investors wonder if fear of Ebola could keep travelers from flying. Shares dove deeper after it came out that a nurse who would later be diagnosed with the disease took two domestic flights the week before she was isolated for treatment.

Airlines are going out of their way to reassure travelers that it’s still safe to get on a plane. U.S. airline companies are cooperating with the government to put new screening measures in place to catch sick passengers, says Nick Calio, CEO of Airlines for America, a trade association. “Because of these coordinated efforts, we believe discussions of flight bans are not necessary and actually impede efforts to stop the disease in its tracks in West Africa,” Calio wrote in a statement.

A travel ban could have economic consequences beyond the obvious dip in business and share values, says Gabriel Mathy, a professor of economics at American University. “It’s more of a problem in terms of the future,” Mathy says. “If we have these kind of travel bans, it’s going to signal to Africa that they can’t really rely on openness in the West.” This kind of a signal could continue to have an adverse affect on international trade, even after a temporary ban is lifted.

More immediately, says Mathy, the stock market as a whole could take a hit if a ban were imposed. The government’s current reluctance to take the step implies confidence, he says, but a change of heart could spark a market panic. “If they have to impose a travel ban, it means that maybe things are spiraling out of control, and I think that could have some big economic consequences.”

A travel ban could also get in the way of medical work in West Africa. Doctors Without Borders is one of the most active groups fighting Ebola in the region. Tim Shenk, a spokesman for the the aid organization, says the Ebola epidemic calls for measures that make it easier to transport people and resources, not harder. “It is crucial that airlines continue flying to the affected region,” he says.

Big name lawmakers are leading the calls for a ban. Senate Minority Leader Mitch McConnell and Sens. Ted Cruz and Marco Rubio have spoken out in favor of travel restrictions. House Speaker John Boehner also threw his hat in the ring when he said the president should “absolutely consider” a travel ban.

But the White House has repeatedly said that a ban is not on the table, and health officials from the Centers for Disease Control and Prevention, and the National Institutes of Health warned Congress Wednesday that a ban could actually make accounting for sick travelers much more difficult.

It’s possible a ban isn’t necessary to reach the goal of keeping sick travelers out of the U.S. The government already has the authority to screen travelers for health issues when they arrive in the U.S., says Vladeck, and it can quarantine those who could potentially be contagious — even against their will. “And so the real question for anyone proposing an outright travel ban,” he says, “is why those measures, if properly administered, would be insufficient to protect against the domestic spread of the disease.”

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This article originally published at National Journal here