In the spring of 1980, Congress was having a shutdown fight that might be considered tame by today’s standards.

The Federal Trade Commission, then a 65-year-old regulatory agency with 1,600 employees, was running out of money and needed Congress to pass a spending bill for the next fiscal year. Some lawmakers, pushed by lobbyists for the broadcast and sugar industries, would only green light more money if the agency’s rulemaking and investigative powers were drastically curbed. Meanwhile, President Jimmy Carter refused to sign any bill that would undermine the FTC.

Wondering whether a federal agency could legally allow its employees to continue working if its appropriations had dried up, Carter sought legal clarity from his attorney general, Benjamin Civiletti.

Civiletti delivered an opinion nearly 40 years ago that paved the way for government shutdowns, including the current partial closure, now the longest in U.S. history.

“MY DEAR MR. PRESIDENT,” he wrote to President Carter on April 25, 1980, “It is my opinion that, during periods of ‘lapsed appropriations,’ no funds may be expended except as necessary to bring about the orderly termination of an agency’s functions.” Civiletti added that the expenditure of additional funds without congressional approval would violate the Antideficiency Act of 1870. He said the law’s language was “plain and unambiguous,” and that it barred agencies from “incurring pay obligations once its authority to expend appropriations lapses.”

Civiletti, a trusted lieutenant and former assistant U.S. attorney in Baltimore, was making a blunt argument: Either Congress keeps a government agency alive and pays its people, or it starves the agency of funding and no one works or gets paid.

The opinion shocked the government, particularly those who worked at the FTC.

A week later, the FTC was temporarily shut down, “apparently the first federal agency ever forced to close its doors in a budget dispute,” according to a Washington Post article from May 1, 1980. “The shutdown came despite eleventh-hour congressional action to limit sharply the agency’s power.”

One FTC official, speaking on the condition of anonymity in order to talk freely, told the Post: “We are in the absurd situation of having to follow the attorney general’s opinion.”

As the agency wound down its operations, 11 FTC investigators scouring documents from an oil company in Texas were ordered home, according to The Post. An FTC argument scheduled before a New York federal appeals court was scratched. “The machines that normally test about 500 cigarettes a day for the Federal Trade Commission went cold turkey yesterday,” The Post reported in a front-page story.

FTC Chairman Michael Pertschuk was not pleased.

“It’s basically idiotic. It’s a waste of taxpayers’ dollars,” he said, citing the travel expenses incurred by the shutdown.

Sounding much like today’s furloughed government workers, lower-level employees said they felt discarded and meaningless. “It’s just degrading,” Sue Hendsey, the FTC’s chief librarian, told The Post. “Morale is low, to say the least.”

But the FTC wasn’t shut down for long, only a few days.

Now retired, Civiletti, 83, who splits his time between Florida and Baltimore, said in a telephone interview that the modern era of government shutdowns has surprised him.

“I couldn’t have ever imagined these shutdowns would last this long of a time and would be used as a political gambit,” he said. My opinion “was a purely direct opinion on a fairly narrow subject and has been used in ways that were not imagined at the time.”

Under President Ronald Reagan, there were two government-wide shutdowns between 1981 and 1984, but they lasted one full day and a half-day, respectively, according to historian and lawyer Kenneth D. Ackerman. Later, in 1990, the administration of George H.W. Bush experienced a shutdown that lasted over Columbus Day weekend.

It wasn’t until the mid-1990s when Civiletti’s legal opinion truly started being exploited, according to Ackerman, who posted an article on its impact earlier this month on his law firm’s website. (Headline: “Government shutdowns — Who dreamed up this crazy idea?”)

The last record-long government shutdown occurred under the Bill Clinton administration, when Republicans controlled the House. Thousands of federal workers were furloughed. From Dec. 16, 1995, to Jan. 6, 1996, Washington all but went dark. Museums closed, taxis idled and cruised, and hotels and restaurants trimmed staff. Finally, on the day workers were scheduled to return to work, not one but two winter storms hit the Washington area, making it impossible for offices to open for another five days.

“The whole idea that someone would shut down government in order to gain leverage over a political opponent was not part of the discussion in 1980,” Ackerman told The Post. “The framers of the Antideficiency Act of 1870 did not conceive that they were making a political weapon.”

Neither did Civiletti.

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