With the firing of Attorney General Jeff Sessions, America is in uncharted territory. The last time a president made a personnel change to undermine an investigation of his associates, Congress forced him to resign. That was when President Richard Nixon pushed out his attorney general and deputy attorney general so he could fire the special prosecutor. The fallout from this Saturday Night Massacre, as it is known, has stood as a warning to subsequent presidents. Yet President Trump has launched a piecemeal Saturday Night Massacre of his own. He first fired FBI Director James Comey last year for his handling of the Russia probe, then he fired the attorney general for failing to protect him from the Russia probe. His intent to undermine an investigation of his campaign has been clear throughout—he barely tried to hide it—but the difference this time is that he has acted with impunity. What comes next could be anything.

The thing about traveling in uncharted territory is that you don’t know where you’ll end up. This may seem like a simplistic observation, but it’s one worth making. Uncharted territory is the last place a conscientious government official wants to be and the first place an unscrupulous one wants to go. Precedents and norms are guideposts along well-traveled paths in government that lead to impartial decision-making. Conscientious officials find these guideposts helpful as they continuously check their motives to make sure they are putting the public’s interests ahead of their own and other private interests. If circumstances deliver them into uncharted territory, it becomes harder to gauge whether they are serving the public’s interest.

Forty-five years ago, the leaders of the Department of Justice found themselves in similar uncharted terrain. An unscrupulous president was attempting to abuse his authority to undermine a special counsel investigation of individuals associated with his campaign for reelection. Special prosecutor Archibald Cox had demanded President Richard Nixon’s tapes of White House deliberations. Nixon responded by negotiating a compromise with Attorney General Elliot Richardson that would have allowed him to withhold the tapes, summarize the contents of some of them, and let a third party verify his summary.* But Cox rejected the compromise, so Nixon ordered Richardson to fire him.

I imagine Richardson felt a long way from the familiar paths of government service and their reassuring guideposts. He had no way of knowing how history would judge his impossible dilemma. However things may look to us decades later, the outcome was not inevitable. Had Richardson been unscrupulous, he could have asked the Justice Department’s Office of Legal Counsel for an outcome-driven opinion justifying the politically motivated personnel change.

At the time, a Johnson-era executive order on ethics was still on the books. Its first section declared: “Where government is based on the consent of the governed, every citizen is entitled to have complete confidence in the integrity of his government.” The order went on to command, “Each individual officer, employee, or adviser of government must help to earn and must honor that trust by his own integrity and conduct in all official actions.” Few could dispute the virtue of this executive order, but ideas about its real-world application may have varied.

The best way to interpret the executive order was to consider what it did not say. The executive order did not say that each officer, employee, or adviser should blindly comply with a corrupt presidential order. Instead, its ethical mandate reflected the constitutional structure of a government that places the rule of law above the president. The current framework for ethics in the executive branch similarly demands loyalty to the Constitution, laws, and a set of 14 ethical principles rather than slavish obedience to the president’s every whim.

Richardson recognized that he could not both fulfill his ethical mandate and comply with Nixon’s order. Instead, he resigned in protest. His deputy, William Ruckelshaus, also ended his tenure at the Justice Department by refusing to carry out the order that would ultimately end the Nixon presidency. What prevailed that day was an abiding loyalty to something bigger than a president.

But things might have been different were Richardson not in uncharted territory. Suppose Nixon had not been the first president in modern times to undermine an investigation of his close associates with a personnel change. Suppose the Office of Legal Counsel had issued an opinion supporting a previous president’s corrupt personnel action. The ethical mandate would likely have been interpreted in the context of that prior precedent. Then, it would have been Richardson and not Nixon who was breaking governmental norms. History might have been on Nixon’s side.

In 2018, we again find ourselves charting new territory. The argument that Comey’s firing might not be a catastrophe for democracy was that we now had Robert Mueller in the role of special counsel. The argument that Sessions’ firing might not be a catastrophe for democracy is that Mueller’s investigation may yet overcome any obstacles and reach its natural conclusion.

In 2018, we again find ourselves charting new territory.

Maybe, maybe not. But whatever the outcome of Mueller’s investigation, America is establishing new precedents. One precedent is that President Trump fired the FBI director—and Congress did nothing. Another is that Trump admitted the FBI’s investigation of his campaign motivated the firing—and Congress did nothing. A third precedent is that Trump fired the attorney general after having railed against him publicly for refusing to intervene in the investigation—and Congress has done nothing. A fourth precedent is that Trump circumvented the Justice Department’s order of succession so he could replace the attorney general with an individual who has directed partisan attacks at the special counsel, has described publicly how a new attorney general could undermine the investigation, has had a personal and political relationship with an individual involved in the investigation, and has been associated with a company that is the focus of a separate FBI investigation.

We’ll see what a new Congress does about that when it is sworn in this January, but options may be limited unless the Senate’s leadership has a change of heart. Even if the appointment of Acting Attorney General Matthew Whitaker—the current replacement for Sessions—were to be invalidated, Trump would still be guilty of having fired the nation’s top two law enforcement officials in an effort to obstruct the investigation of his campaign.

If members of Congress or the American people fail to act, these precedents will become the guideposts for future presidents who follow the path President Trump is blazing. A new tenet of American democracy will become that a president is permitted to evade investigation by firing the heads of agencies that investigate the president’s close associates, even when the investigation is the reason for the firings. This cannot stand. Putting a president above the rule of law is a threat to democracy.

*Correction, Nov. 14, 2018: An earlier version of this article misspelled the name of former Attorney General Elliot Richardson as Elliott Richardson.