When the historian Allan Lichtman published his best-selling book The Case for Impeachment in April 2017, Donald J. Trump had not been in office for even three months. The following month, a handful of Democrats in Congress, led by Rep. Al Green of Texas, supported articles of impeachment, but at the end of the year, Mr. Green could not even convince most of his party colleagues to agree. Much has changed since then. After the publication of the Mueller report on Russian interference in the 2016 U.S. presidential election, support for impeachment grew but was still short of a majority in the U.S. House. Only after reports that Mr. Trump pressured the government of Ukraine to produce damaging information about former Vice President Joseph R. Biden Jr. (who may face him in the next election) did impeachment become a likely possibility.

So what exactly does impeachment mean? Why do we even have an impeachment process when we can just vote the president out of office?

“I think the framers of the Constitution saw the electoral process as the roots for changing who might occupy the office or not,” said John D. Feerick, the Norris Professor of Law at Fordham University School of Law and dean emeritus, in an interview with America. “But [they] did feel that there needed to be a process to deal with abuse of power…. A public official, in the case of a president, vice president or other civil office of the United States, has enormous power, and the conduct with respect to those powers [is what] raises the question of the impeachment process.”

The framers of the Constitution did feel that there needed to be a process, outside of elections, to deal with abuse of power.

Mr. Feerick assisted in the drafting of the 25th Amendment of the Constitution, which was ratified in 1967 and deals with matters of presidential succession and removing the president in the case of “incapacitation.” He has written frequently about presidential succession and impeachment.

Impeachment is clearly defined in Article I of the U.S. Constitution, which states that “The President, Vice President and all civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors” and declares that “the House of Representatives shall have the sole Power of Impeachment.” The punishment applied by impeachment and conviction is limited but substantial, including “removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States.” Furthermore, impeachment does not preclude the prosecution of the president after removal from office: “but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.” An impeachment and removal from office, therefore, does not mean that further criminal and/or civil charges cannot be brought against the individual.

Impeachment is just the beginning of a process that may or may not conclude with the removal of a public official. For now, the U.S. House has only committed to an impeachment inquiry, in which hearings are held (typically, but not necessarily, by the House Judiciary Committee), witnesses called, and evidence reviewed. A public official is officially impeached if a majority of the House of Representatives supports at least one article of impeachment; the Democrats currently hold a majority of seats in the chamber.

“It’s the equivalent of an indictment, and there needs to be a trial of the charges that got expressed in the articles of impeachment,” Mr. Feerick said. After a trial in the Senate, presided over by the chief justice of the U.S. Supreme Court, that body votes on whether the president is guilty of the charges. This time, two-thirds of the members would have to reach a guilty verdict. Because neither party controls that many Senate seats, conviction would have to be bipartisan.

The Constitution is very specific in identifying the instances in which impeachment may be applied—again, “Treason, Bribery, or other high Crimes and Misdemeanors.” There are federal statutes defining bribery, and treason is clearly identified in Article III of the Constitution as “consist[ing] only in levying war against them, or in adhering to their enemies, giving them aid and comfort,” but “high crimes and misdemeanors” is ambiguous and vague.

The phrase “comes from the common law,” said Mr. Feerick, adding that he thought the writers of the Constitution were referring to “how you used your office and a corrupt and evil and wrong use of power that’s damaging the society, the country.”

“If you go back to the Constitutional Convention,” he said, “it was George Mason who…said that we have to have more in the Constitution than ‘treason’ or ‘bribery’ because of the possibility of someone misusing power in a serious way.” Hence, “high crimes and misdemeanors” went into the Constitution.

Impeachment is a rare occurrence in U.S. history. In the 230 years following the ratification of the Constitution, the House of Representatives has held 62 impeachment proceedings and approved articles of impeachment against 19 public officers. These affirmative votes involved 15 federal judges, two presidents (Andrew Johnson and William J. Clinton), one cabinet officer and one U.S. senator.

“This is the oldest written constitution in the world, and it has impeachment.”

Asked why so few of the thousands of potential cases for impeachment move forward, Mr. Feerick said there is a “high bar that has to be satisfied in the area of impeachment. Two houses of Congress are involved. And…you have the chief justice of the United States leaving one’s duty on the [Supreme] Court in order to preside at such a trial. It contemplates egregious acts to take someone through the whole impeachment process.”

Some question whether impeachment is the best response to a government official who betrays the public trust. It takes significant amounts of work on the part of legislative committees, and it takes the attention of Congress away from its usual legislative duties.

But as Mr. Feerick pointed out, “The removal is made difficult so as to respect the voice of the people in choosing a president.”

There are significant challenges ahead for Congress. One chamber may find reasonable cause to move forward and the other insufficient evidence to convict. The political backlash on both sides of the aisle may be substantial for those who support and oppose impeachment. It is unknown whether the president will face criminal charges following his tenure in office or whether he will be pardoned by a successor. Richard Nixon resigned the office of the presidency during ongoing impeachment inquiries and, upon his resignation, the impeachment proceedings immediately terminated. However, he still faced potential criminal prosecution. It was only when Gerald Ford pardoned him that he was free from any potential criminal liability for his actions.

One thing is clear: Impeachment, a political remedy to a political problem, does not occur in a vacuum and the implications must be carefully managed. So why attempt a removal from office when an election could take care of the issues before our nation?

“I am somebody that accepts the wisdom of the framers of the Constitution, who would find it astonishing the number of people we have in the country today and who would be astonished by the social media, communications and advanced travel,” said Mr. Feerick. “But they gave us something very foundational. A written constitution that laid out their judgment, and part of that constitution was an impeachment process, and I would say that their wisdom has stood us tall as a nation.”

“This is the oldest written constitution in the world, and it has impeachment,” he added.

The framers’ intent was to establish a republic rooted in stability, and a key component of that stability is the ability to hold government officers accountable. They sought to identify those who betrayed the public trust, regardless of political affiliation, ideology, creed or belief, and to ensure that they never did it again.

Nicholas D. Sawicki is associate director of development for the Archdiocese of Galveston-Houston and a frequent contributor to America.