For hundreds of thousands of federal employees, the “involuntary servitude” that Young describes could continue indefinitely. President Donald Trump warned Democratic leaders last week that he could keep the government shuttered for “months or even years”—a scenario that union leaders told me they had never before contemplated. “A lot of things are possible under this president, so I think we have to start preparing,” said Randy Erwin, the president of the National Federation of Federal Employees.

Government shutdowns have only been a feature—or, more accurately, a bug—of fiscal impasses since the enactment of the modern congressional budget process in the 1970s. The current shutdown is a partial one affecting roughly 800,000 federal employees. Roughly half of them are on furlough, while the other half, whose jobs are considered essential to public health and safety, must report to work even though Congress has not appropriated the funds to pay them. This category includes the Secret Service agents who protect the president and his family, the Transportation Security Agents, pilots, and air-traffic controllers who keep the aviation system running, the corrections officers who staff federal prisons, and, yes, the Border Patrol agents who guard the southern divide with Mexico along which Trump wants to build a wall.

If they don’t show up, “they’d be considered absent without leave,” said Jacque Simon, the policy director for the American Federation of Government Employees, by far the largest union representing federal employees. “When they’re told to come to work, they are required to come to work.” An AWOL designation could lead to disciplinary action, including termination. For longtime government employees, that could put in jeopardy a federal pension they’ve spent a career accruing, union leaders said.

By and large, federal employees have been reporting to work. The TSA has acknowledged, in response to a CNN report last week, that its agents have called out sick at higher rates since the shutdown began, but the TSA spokesman Michael Bilello said that the sick calls have had a “minimal impact” on air travel or wait times. The sick calls do not, as yet, appear to be widespread. Bilello said that 4.6 percent of employees had called out sick on Monday, compared with 3.8 percent of employees on the same date in 2018. “We understand that the current lapse in funding may be causing added stress for our workforce and want to continue to express that we are grateful to the more than 51,000 officers across the country who remain focused on the mission,” he tweeted.

Faced with a potentially indefinite shutdown, the unions have turned to the courts for relief. The American Federation of Government Employees has filed a lawsuit against the Trump administration alleging that by requiring employees to work without pay, the government is in violation of the Fair Labor Standards Act, a 1938 law that mandates a minimum wage and overtime pay both to public- and private-sector workers. Another federal labor group, the National Treasury Employees Union, has filed a similar suit.