(CNN) - As the Trump administration recalls tens of thousands of government workers to restart operations previously closed during the partial shutdown, one expert says the law allows fairly wide latitude to decide which government functions are essential.
On Thursday, the State Department announced that its employees would return to work in the coming days.
Alice Rivlin, who directed the Office of Management and Budget under the Clinton administration, said the guidelines were not particularly clear and that officials could revisit their assessments as shutdowns dragged on.
"The law itself is pretty vague," Rivlin told CNN. "It's a question of what's essential and what isn't. ... In the end it's a judgment call."
The Antideficiency Act, which guides many of the decisions around a government shutdown, provides this broad guideline: "emergencies involving the safety of human life or the protection of property." It does specify that language cannot be used to justify "ongoing, regular functions of government the suspension of which would not imminently threaten the safety of human life or the protection of property."
Those decisions are generally the domain of the Office of Management and Budget.
"Our mission from the President has been to make this shutdown as painless as possible, consistent with the law," Russ Vought, the current deputy director of OMB, told reporters earlier this month.
He ticked off some of the administration's adjustments to make that happen, such as recalling IRS workers to process tax refunds, reversing plans to stop issuing flood insurance policies and bringing back rangers to clean up national parks.
"In some cases, activities and performance would not qualify for continuation during a very brief funding lapse ... but they would qualify if the duration of the funding lapse became longer," reads a December guide from OMB to federal agencies.
Rivlin, who led OMB during a 21-day shutdown that had been the longest until the current one surpassed it, said she believed it was appropriate to include flexibility in the laws and guidelines, as it allowed the administration to adapt as circumstances changed.
She had urged her Clinton administration colleagues to make decisions that visually reminded Americans that their government was closed, such as by cutting power to the National Christmas Tree.
"I said I didn't think the Christmas tree was essential. That one got a lot of screams and a lot of volunteers" to keep it lit and operating, she said. "I thought that was unfortunate. I thought we wanted to make as clear as possible that the shutdown was inconveniencing people."
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