Trump impeachment: Here's how the process works

The House of Representatives is set to take up an unprecedented second impeachment case against President Donald Trump for his role in last week's riot and siege of the U.S. Capitol.

If passed, the extraordinary step, just days before Trump is set to leave office, would mark the first time in history that a sitting president was impeached twice. Only two other presidents -- Andrew Johnson and Bill Clinton -- have been impeached and none have been convicted.

House Democrats filed a single article of impeachment on Monday against President Donald Trump for "incitement of insurrection" following the violent siege that left one Capitol police officer and four others dead and left members of Congress and their staffs fearing for their lives.

Unlike his first impeachment in 2019, some House Republicans have indicated that they supported the effort. And underscoring the uncharted nature of the circumstances, the Senate trial could come after Trump leaves office.

On Jan. 6, Trump addressed a crowd of supporters hours before they marched to the Capitol, where a joint session of Congress was underway to certify the election results, and stormed the building. Trump, as he and his allies had done for weeks, continued to spread falsehoods about voter fraud, told the group to "fight like hell" and promised to go with them to the Capitol, though he did not.

Several of the people who have been arrested by federal authorities in connection with the incident are longtime Trump supporters and have told investigators they came to Washington, D.C., to protest the certification.

As he did during impeachment hearings in 2019, when he charged with abuse of power and obstruction of justice for allegedly attempting to coerce Ukrainian officials to provide election interference, Trump called the House's move "the greatest witch hunt in the history of politics."

As of Jan. 12, Trump had not disavowed his comments made before the riot and in fact called them "totally appropriate." He did say that he did not believe in "violence or rioting" and tried to shift blame for anger in the country to Democrats.

Here's how the impeachment process works:

The presidential impeachment process

An impeachment proceeding is the formal process by which a sitting president of the United States is accused of wrongdoing. It is a political process and not a criminal process.

The articles of impeachment are the list of charges drafted against the president. The vice president and all civil officers of the U.S. can also face impeachment.

The process begins in the House of Representatives, where any member may make a suggestion to launch an impeachment proceeding. It is then up to the speaker of the House, as leader of the majority party, to determine whether or not to proceed with an inquiry into the alleged wrongdoing.

Over 210 House Democrats introduced the article of impeachment on Jan. 11, 2021, contending Trump "demonstrated that he will remain a threat to national security, democracy and the Constitution if allowed to remain in office and has acted in a manner grossly incompatible with self-governance and the rule of law."

The impeachment article also cited Trump's controversial call with the Georgia Republican secretary of state where he urged him to "find" enough votes for Trump to win the state and his efforts to "subvert and obstruct" certification of the vote.

It also cited the Constitution's 14th Amendment, noting that it "prohibits any person who has 'engaged in insurrection or rebellion against' the United States" from holding office.

House Speaker Nancy Pelosi has indicated that she is looking to vote on the article before the inauguration of President-elect Joe Biden. It would require a simple majority vote, which is 50% plus one (218), after which the president is impeached.

If the House impeaches, Trump would face a vote on the article in the Senate.

The timeline of a potential Senate trial and likelihood of conviction are unclear. Senate Republican Leader Mitch McConnell said he won't bring back the Senate from recess before Jan. 19, which could push a trial into the beginning of the Biden administration.

Justification for impeachment

When it comes to impeachment, the Constitution lists "treason, bribery, or other high crimes and misdemeanors," as justification for the proceedings, but the vagueness of the third option has caused problems in the past.

"It was a central issue with Andrew Johnson, and there was a question during Clinton's proceedings about whether his lie was a ‘low’ crime or a ‘high’ crime," Michael Gerhardt, a constitutional law professor at the University of North Carolina who authored a book on the impeachment process, told ABC News.

According to Suzanna Sherry, a law professor at Vanderbilt University who specializes in constitutional law, "nobody knows" what is specifically included or not included in the Constitution’s broad definition of “high crimes and misdemeanors.”

"It’s only happened twice and so the general thought is that it means whatever the House and the Senate think it means," Sherry said before Trump's first impeachment, and even if the House approves the article or articles of impeachment, the senators can choose to vote against the articles if they feel they are not appropriate.

Where does the Senate come in?

The Senate is tasked with handling the impeachment trial, which is presided over by the chief justice of the United States. To remove a president from office, two-thirds of the members must vote in favor – at present 67.

If the Senate fails to convict, a president is considered impeached but is not removed, as was the case with both Clinton in 1998 and Andrew Johnson in 1868. In Johnson’s case, the Senate fell one vote short of removing him from office on all three counts.

While the Senate trial has the power to oust a president from office, and ban him or her from running for future office, it does not have the power to send a president to jail. Disqualification from holding office, a separate process, requires a simple majority vote, according to the Congressional Research Service.

"The worst that can happen is that he is removed from office, that's the sole punishment," Sherry said.

That said, a president can face criminal charges at a later point. Sherry points out that in the Constitution "the party convicted shall nevertheless be liable and subject to indictment, trial, judgment and punishment, according to law."

While presidential removal is unprecedented, the vice president would assume office in that case under the 25th Amendment, which was ratified in 1967. Then the new president would nominate a new vice president who would have to be confirmed by a majority of both houses of Congress.

What does an impeachment vote mean for a sitting president and for a former president?

A president can continue governing even after he or she has been impeached by the House of Representatives.

Trump continued to govern after his impeachment in December 2019, and of course ran for reelection in 2020. After Clinton was impeached on Dec. 19, 1998, he finished out his second term, which ended in January 2001, during which time he was acquitted in a Senate impeachment trial. While Clinton continued governing, and the impeachment had no legal or official impact, his legacy is marred by the proceeding.

Although Trump is set to leave office on Jan. 20, he could face severe punishments that would affect his future in politics, if the Senate moves to convict.

Trump could be barred from running from office in the future. This punishment would require only a simple majority vote of the Senate if the chamber votes to convict.

Past presidential impeachments

The House voted to impeach Trump on Dec. 18, 2019 on two articles of impeachment, one for abuse of power and one for obstruction of justice, in connection with his alleged quid pro quo call with the Ukrainian president.

Following a three-week trial, the Republican controlled Senate acquitted Trump on Feb. 5, 2020.

Johnson faced impeachment in 1868 after clashing with the Republican-led House over the “rights of those who had been freed from slavery,” although firing his secretary of war, Edwin Stanton, who was backed by the Republicans, led to the impeachment effort. The articles of impeachment centered on the Stanton event, according to the Senate.

Clinton, whose impeachment was connected to the cover-up of his affair with White House intern Monica Lewinsky while in office, was 22 votes away from reaching the necessary number of votes in the Senate.

Richard Nixon faced three articles of impeachment related to the Watergate scandal, in which he allegedly obstructed the investigation and helped cover up the crimes surrounding the break-in.

But he didn’t let the process get any further, resigning before the House could impeach him.

Editor's Note: This story was originally published in 2017 and has been updated periodically.

Trump impeachment: Here's how the process works originally appeared on abcnews.go.com