…no President or executive officer has been removed from office through impeachment. … Three Presidents—Andrew Johnson, Bill Clinton and Donald Trump—have been impeached by the House of Representatives. None of them were convicted by the Senate.

…the Framers meant for the phrase “high crimes and misdemeanors” to signify only conduct that seriously harms the public and seriously compromises the officer’s ability to continue. If the phrase is given a less rigorous interpretation, it could allow Congress to influence and control the President and the courts.

Impeachment… must be closely limited to situations of conduct that inflicts serious harm on the public and that seriously compromises the officer’s ability to function in office. Otherwise, it could undermine our constitutional system of separation of powers and thwart our fundamental commitment to democracy [the people’s choice through election].

From: https://constitutioncenter.org/interactive-constitution/interpretation/article-ii/clauses/349#the-scope-of-the-impeachment-power

The Scope of the Impeachment Power: What are “High Crimes and Misdemeanors”?

by Neil J. Kinkopf
Professor of Law, Georgia State University College of Law

What sort of conduct is so harmful that Congress is justified in impeaching and removing an officer who commits it? The Constitution’s answer is “treason, bribery, or other high crimes and misdemeanors.” Treason and bribery are clear enough, but the concluding phrase “other high crimes and misdemeanors” is anything but clear.

It is open-ended for the reason many constitutional provisions are vague and open-ended. In the words of the great Chief Justice John Marshall, the “constitution [is] intended to endure for ages to come and, consequently, to be adapted to the various crises of human affairs.” In the context of impeachment, this means that the Constitution cannot be expected to specify in detail every ground on which impeachment is or is not permissible. If it attempted to do so, an individual who should be impeached might evade this punishment because the officer’s conduct does not meet some technical element of the definition even though the officer’s conduct had so harmed the nation that all agree the officer should be removed. Instead, the Constitution sets forth the general principle of impeachment and leaves its more specific definition to be developed by the House of Representatives and the Senate.

In this light, then-Representative Gerald Ford’s claim that the House could impeach an officer on any ground it wishes may seem plausible. But the Ford position goes too far. It ignores the Constitution’s text and structure. If the Constitution means to allow impeachment on any ground whatsoever, then why would the Constitution bother to set forth that impeachment and removal may be based only on conduct that rises to the level of “treason, bribery, or other high crimes and misdemeanors”? In fact, the Framers debated this phrase and settled on this formulation precisely to prohibit Congress from impeaching officers for any reason at all. The Framers were determined to limit the grounds on which an officer could be impeached in order to safeguard another constitutional principle: the separation of powers.

It is clear that, in our constitutional system of government, the executive branch (the President, the cabinet, and other officers subordinate to the President) and the judiciary (the Supreme Court and the lower federal courts) are to be independent from the legislature (the House of Representatives and the Senate). The Framers recognized the potential for impeachment to undermine this principle. It is a well-established legal principle that the power to remove is the power to control. The President, for example, can control the agencies of the executive branch principally because the President can remove the heads of the agencies (such as cabinet secretaries) for any reason at all, including for not following an order from the President. They are said to serve at-will because the President can remove them at will. If Congress can impeach and remove the President or Supreme Court Justices for any reason at all, then these officers serve at the will of Congress and are subject to its control.

An early draft of the Constitution gave Congress the power to impeach and remove officers for “maladministration.” James Madison objected to this because the term was so vague that it would allow impeachment for any reason at all. As he put it, “so vague a term will be equivalent to a tenure during the pleasure of the Senate.” The term “maladministration” was then deleted from the draft and replaced by the phrase “other high crimes and misdemeanors.” This shows that the Framers meant for the phrase “high crimes and misdemeanors” to signify only conduct that seriously harms the public and seriously compromises the officer’s ability to continue. If the phrase is given a less rigorous interpretation, it could allow Congress to influence and control the President and the courts.

There is a second constitutional principle at stake in defining the scope of the impeachment power: our commitment to democracy. Allowing Congress to remove Presidents, and executive officers who serve under them, has the effect of thwarting the will of the people. After all, the President is elected to serve a four-year term. How, in a democracy, can we justify giving Congress (or anyone other than the people, for that matter) the power to overrule a presidential election? This can only be justified on the ground that the President has committed acts so dangerous to the public that the President may not be allowed to remain in office until the next election.

Imagine, for example, if it were discovered that a President was secretly a spy and agent for a foreign power. In that sort of case all would agree that the danger to our constitutional system of government, indeed to our nationhood, is such that it is impractical to wait for a presidential election to remove the President. The Framers agreed on this point too. But this emphasizes just how important it is to limit the power to truly egregious conduct and serious harms to the public. Otherwise, this narrow and speculative potential could undermine our basic commitment to democracy.

The constitutional commitment to democracy could explain an interesting feature of the history of impeachments in the United States: no President or executive officer has been removed from office through impeachment (though the threat of impeachment and conviction hastened the resignation of Secretary of War William Belknap in 1876 on charges of financial corruption). Each of the eight officers to be impeached, convicted, and removed has been a judge. Federal judges are appointed, not elected, and enjoy life tenure—that is, unlike a President who serves a four-year term, federal judges serve until they die or decide to retire. To remove a federal judge, then, does not raise the same sort of concerns about overruling an election that removing an executive branch officer does.

Three Presidents—Andrew Johnson, Bill Clinton and Donald Trump—have been impeached by the House of Representatives. None of them was convicted by the Senate. Andrew Johnson was impeached in 1868, the last year of his term. One important factor in his acquittal was the reluctance of several Senators to vote for impeachment with a presidential election so close at hand. Best, they thought, to let the voters have their say. Similarly, when the Senate met to try and deliberate on the impeachment of President Clinton, many argued that removing him from office would repudiate the judgment of the people who had reelected him.

Impeachment is a powerful tool. It must be closely limited to situations of conduct that inflicts serious harm on the public and that seriously compromises the officer’s ability to function in office. Otherwise, it could undermine our constitutional system of separation of powers and thwart our fundamental commitment to democracy. The Framers wisely recognized these dangers and added the phrase “high crimes and misdemeanors” precisely to limit the scope of the impeachment power to these most egregious circumstances and to prohibit its use beyond them.

NOTE: something is fishy. I found this article impossible to find through both Google and DuckDuckGo, by searching quotes from the article (in quotation marks) or the title (in quotation marks).