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Imagine you’re headed back home to the United States after spending spring break in Mexico. You’re in line at customs at the airport; you feel queasy, but you can’t tell if it’s a hangover or the chorizo you bought from a street vendor. You sweat and groan as you clutch your stomach in pain and, to your surprise, a customs agent who was apparently watching you approaches and asks if you’ve had any flu-like symptoms.

You confirm that you’ve had some, but before you can explain that it could just be from the bad food, he tells you that you’re going to need to be screened for the coronavirus. Fair enough. When you ask what that entails, he responds that you may have to spend some time in quarantine. For how long?

He says he doesn’t know, and he really doesn’t—because this is what Customs and Border Protection (CBP) is authorized to do during a pandemic.

On Wednesday, the World Health Organization designated the coronavirus a pandemic, meaning that the disease is now considered to have spread worldwide. But pandemics also confer extraordinary privileges on US authorities. Last night, Trump announced a ban the next 30 days on travelers flying from Europe to the United States. And an internal CBP pandemic response plan obtained by The Nation outlines the immigration and border agency’s ability to actively surveil and detain individuals suspected of carrying the illness.

Titled “Operations Plan for Pandemic Response” and marked for official use only, the document was drafted during the avian flu pandemic of 2007. It’s a blunt statement of authority, describing Customs and Border Patrol overseeing potential tent cities of quarantined detainees at the border and coordinating with unspecified intelligence agencies—both foreign and domestic—as well as the Pentagon.

Though the plan was drafted during the Bush administration, it remains CBP’s most recent pandemic response plan and is still in effect, according to a Department of Homeland Security source who provided The Nation with the document. A memo dated February 28 of this year, signed by CBP’s Acting Commissioner Mark Morgan and reviewed by The Nation, made reference to the pandemic response plan.

“Be assured, CBP is ready,” Morgan wrote. “We have a CBP national pandemic plan as well as continuity of operations plans.”

CBP did not respond to a request for comment.

The document contains a number of startling assumptions, like the following: “Pandemic influenza…may challenge the essential stability of governments and society.”

Provided a copy of the document, Katherine Hawkins, senior legal analyst with the Project on Government Oversight, expressed concerns about how the administration might use these powers on immigrants.

“Given the [Trump] administration’s animus for noncitizens, I worry a lot about what they would do with these authorities even when those authorities make sense for a government to have in a public health crisis,” Hawkins said.

Her concerns appear well founded, as the document makes repeated reference to CBP and Immigration and Customs Enforcement’s (ICE) role in transferring and detaining infected travelers—at one point alluding to “tent cities” erected for such a purpose.

The document states: “Due to the distance from CDC Quarantine Stations, some [CBP] locations will require areas designated for medical segregation to safely detain travelers potentially infected with the pandemic flu virus, thereby, helping prevent the spread of the virus to other detainees, travelers, and CBP employees.”

And: “CBP Directors of Field Operations and Chief Patrol Agents will jointly inventory their detention and isolation facilities, and identify other areas that may be utilized for these purposes, e.g., ‘tent cities’ with portable latrines.”

Asked what justification might exist for such sweeping authorities in responding to a pandemic, James Hodge, director at the Center for Public Health Law and Policy at Arizona State University, appeared to think that there were arguments for and against.

“While travel restrictions is not something that CDC favors, it can be useful. There’s a couple reasons you’d shy away from it: It can be discriminatory and it can be problematic,” Hodge said.

Hawkins also expressed concerns about the potential for immigration facilities to spread illness.

“I’m worried about…the role that CBP or ICE facilities can play in spreading diseases. The conditions that were described by the Inspector General’s report—cramming people into cells, telling people they don’t need soap,” Hawkins said. “You could end up with people detained in the border patrol holding cells in horrible conditions for much longer than those cells were ever meant to hold anyone.”

Indeed, the document’s legal annex notes that it’s not even clear how long CBP could detain individuals who are ill.

The annex states: “The details regarding a typical detention period initiated under Title 42 authorities is still unclear. HHS [Department of Health and Human Services] has not provided enough information, as of yet, to permit a legal determination as to the permissible scope and maximum length of a period of detention that has been effectuated by CBP personnel.”

Aside from detention, the document also describes the forms of surveillance and intelligence gathering CBP is authorized to conduct during a pandemic. In many cases, these CBP personnel have not even been given medical training.

“CBP will monitor domestic and international intelligence information to provide continuous situational awareness of national threats.”

The document goes on to describe how any intelligence that CBP collects is to be disseminated at the highest levels of the agency in a “bi-weekly pandemic influenza briefing to the Commissioner and senior CBP personnel and as needed or required in light of new intelligence developments.”

Repeated reference is also made to the fear of terrorists weaponizing the 2007 pandemic. One passage describes how CBP intelligence operations will “monitor terrorist groups for possible attempts to cause an intentional pandemic.”

“Smugglers and terrorists will seize this opportunity to further their own interests. This includes the potential for bio-terrorist use,” the document notes, in a list of “assumptions.”

A number of other startling assumptions are contained within the document.

One passage states:

Many Americans will die from the virus, spreading fear and panic among the population, including CBP employees…. Pandemic influenza is expected to cause massive disruptions in travel and commerce, and may challenge the essential stability of governments and society. In spite of this, CBP must continue to carry out its priority mission to prevent the entry of terrorists and their weapons, regardless of the circumstances.