Government corruption was a major concern when the framers of the US Constitution met in Philadelphia in 1787 for the constitutional convention.

James Madison, the man who would become known as the father of the Constitution, spoke of it often during the weeks of tedious debate over what form the country’s law and leadership should take and what limitations would prevent crooked dealings.

On June 18, when the convention’s delegates were discussing just how long a president should serve, Madison proposed a life term, as long as the executive didn’t misbehave. Some proposed seven years, but Madison objected, arguing that this would only make the president ambitious to prolong his power. The record of the convention reports Madison explaining: “An Executive for life has not this motive for forgetting his fidelity, and will therefore be a safer depository of power.”

While Madison lost the battle for a lifelong presidential term, he did correctly assess the vulnerability of elected presidents. And his concern seems prescient in light of the impeachment inquiry into president Donald Trump’s Ukraine dealings.

Trump is being investigated for his efforts to pressure the Ukrainian government of Volodymyr Zelensky to probe former vice president Joe Biden, the president’s political rival in the 2020 elections. The commander in chief delayed the release of appropriations to Ukraine, allegedly to further his goals. He enlisted his personal attorney Rudy Giuliani to meet with Ukrainians to advance the personally motivated investigation, as well as a public officer, attorney general Bill Barr.

Still, Trump has been utterly unapologetic about his actions. He admits to it all and says he’s done nothing wrong. In fact, he even urged the Chinese government to investigate Biden’s activities in China on national television, doubling down on the alleged corruption by doing it in public, perhaps to prove there is nothing illegal about it.

The framers would not approve. University of North Carolina constitutional law professor Michael Gerhardt, an impeachment expert, argues that the constitutional convention’s record shows the framers were concerned with corruption of all kinds. They understood that it could take many forms, and that’s why an impeachable offense doesn’t have to be a statutory crime to run afoul of the constitution.

Speaking on a call about impeachment law sponsored by the American Constitution Society on Sept. 4, Gerhardt said the framers recognized that an act by the president might undermine the public interest or the office itself even if it’s not expressly included in a criminal statute. One of the articles of impeachment against Richard Nixon, for example, accused him of ordering the IRS to go after his political rivals. Gerhardt points to this as evidence that though there may be no specific criminal statute to address the presidential action, the presidential corruption can still be prosecuted through impeachment.

“The Declaration of Independence is basically a set of impeachment articles against the king [of England],” Gerhardt said. In light of this, it seems likely the framers would want to investigate a president who may have used his public office for personal gain while compromising national security.

That’s why the impeachment option was always on the table at the constitutional convention. A proposed draft of the government designed by Charles Pinckney, submitted early in the convention, states: “The Executive Power of the United States shall be vested in a President of the United States of America…He shall be removed from his office on impeachment by the house of Delegates & Conviction in the Supreme Court of Treason bribery or Corruption.”

Some experts say there is no question about whether Trump has been corrupt. Mieke Eoyang, the vice president of national security policy at center-left think tank Third Way, told the American Constitution Society’ audience, “The conduct of Trump is a-historic. We have not seen a US president use his public power to advance his personal interest this way before. But the framers were concerned about this.”

Eoyang points out that Trump’s actions put Americans on “terra incognita” with respect to corruption. ”Trump has turned the definition of corruption on its head by asking foreign governments for opposition research,” Eoyang argues. She says his objections to the impeachment inquiry are merely meant to distract from the real wrongdoing and harm to the country caused by his efforts in Ukraine. Apart from campaign finance law barring a politician from taking something of value from a foreign government for personal interests—which opposition research is—the president’s conduct “implicates treason, bribery, and emoluments,” she said.

While some legal experts have questioned whether Trump committed any crimes, Eoyang and Gerhardt insist that it’s evident from the concerns surrounding corruption in the creation of the constitution that if a politician uses public office for personal gain, it’s an impeachable offense. Vulnerability to foreign powers due to personal weakness in representatives scared the framers. As Alexander Hamilton put it at the constitutional convention, “One of the weak sides of Republics was their being liable to foreign influence & corruption. Men of little character, acquiring great power become easily the tools of intermeddling Neibours.”

So if the president put pressure on Ukraine to investigate his rival to advance the Trump 2020 campaign, it wasn’t just okay or normal by constitutional standards, and it warrants investigation. Gerhardt calls the situation “stunning,” saying, “Why isn’t everyone concerned? It’s a no-brainer there was self-dealing.”