- On December 18, President Donald Trump was impeached by the House of Representatives.
- On February 5, he was acquitted on both charges after a Senate trial.
- Only three US presidents have faced impeachment — Andrew Johnson in 1868 and Bill Clinton in 1998 were both impeached, while Richard Nixon resigned before he could be impeached in 1974.
- No president has ever been convicted. That hasn't changed.
- Visit Business Insider's homepage for more stories.
President Donald Trump, the third president in history to be impeached, was acquitted on Wednesday.
In the fall, Congress investigated whether Trump pressured Ukraine to investigate his political rival, Democrat presidential candidate Joe Biden, and his son.
On December 13, the House Judiciary Committee voted to advance two impeachment articles against Trump — one for abusing his office, and the other for obstructing Congress. On December 18, he was impeached on both articles.
On February 5, he was acquitted on both charges. For the abuse of power charge, 48 senators, including Republican Sen. Mitt Romney, voted to convict Trump, while the other 52 Republican senators voted to acquit him.
For the obstruction of Congress charge, the final vote was along party lines— 53-47.
Impeachment is a power Congress has to remove presidents or other federal officials from office if enough lawmakers find that they have committed "treason, bribery, or other high crimes and misdemeanors."
First there's the investigation, then the House of Representatives votes on whether to impeach and charge them with any crimes, and if a majority votes in favor, then a Senate trial determines whether they're guilty and the penalty.
Three other presidents have faced impeachment proceedings.
In 1868, Andrew Johnson was impeached for breaching the Tenure of Office Act, but the Senate narrowly acquitted him by one vote. In 1974, Richard Nixon faced an impeachment inquiry, but he quit before he could be impeached. In 1998, Bill Clinton was impeached, but he was acquitted by the Senate.
Only 11 days had passed after a whistleblower complaint before Pelosi announced an impeachment inquiry, Axios reported. For Nixon, it took 599 days from the Watergate break-in to an inquiry, while for Clinton it took 260 days from the first news report of an affair to an inquiry.
Here's how the process went for the four presidents who faced impeachment.
SEE ALSO: 61 photos show the key moments of Trump's impeachment
DON'T MISS: The impeachment inquiry into Trump, explained in 60 seconds
Former President Andrew Johnson was the first sitting president to ever face impeachment proceedings.
Source: Senate
It all began when he removed his Secretary of War Edward Stanton from office in 1867, which breached the Tenure of Office Act.
The law meant he couldn't fire any important officials without first getting Senate's permission. At first, he'd suspended Stanton and replaced him, but when Congress intervened and reinstated Stanton, Johnson fired him on February 21, 1868.
Three days later, on February 24, 1868, the House of Representatives impeached Johnson by a vote of 126-47.
The House said he'd violated the law, and disgraced the United States' Congress.
From March to May 1868, over 11 weeks, the Senate tried Johnson's case, and finally voted to acquit him. The vote was 35 guilty to 19 not guilty.
One more guilty vote would have met the required two-thirds that's necessary for a conviction. Seven Republican senators broke with their party and voted to acquit Johnson, who was a Democrat.
Over 100 years later, the two-year crisis that would lead to Nixon's resignation began on June 17, 1972, when five men were arrested after breaking into the Democratic National Committee's headquarters at the Watergate hotel in D.C.
They were caught trying to bug the building. A year later, on January 8, 1973, the trial for Watergate began. By the end of April, two senior White House officials and the attorney general had resigned over the controversy. The White House counsel was fired.
In July, Nixon refused to hand over taped phone calls, which were thought to connect Nixon to the burglary and its cover-up. They are known as the "Nixon tapes."
Nixon cited executive privilege as the reason for not handing them over to Congress (even under subpoena), and the Supreme Court later unanimouslyruled that he had to.
In October, more controversy followed, including several high White House officials resigning rather than following Nixon's order to fire special prosecutor Archibald Cox, who was leading the investigation into misconduct by Nixon.
This event was known as the "Saturday night massacre." A month after it, Nixon gave his famous line: "I am not a crook."
On May 9, 1974, the House Judiciary Committee began impeachment proceedings against Nixon. The House of Representatives authorized the proceedings with an overwhelming vote of 410-4.
Sources: PBS, Los Angeles Times
By July 1974, the House Judiciary Committee found Nixon had obstructed justice, misused his power, and was in contempt of Congress. The three charges were sent to the floor for a full House vote.
Source: PBS
But before the house could vote to impeach Nixon, he resigned on August 8, 1974. He is the only president to ever resign.
If he had been impeached, he would have been tried in the Senate and he could have been convicted.
From early 1994, President Bill Clinton was dealing with scandals and politically motivated investigations, beginning with a financial investigation known as "Whitewater."
Source: The Guardian
That same year, Paula Jones sued him, accusing the president of sexual harassment.
Clinton argued he had presidential immunity from civil cases, but in 1997, the Supreme Court rejected his argument.
In January 1998, during Jones' case, Clinton denied under oath that he'd ever had an affair with White House intern Monica Lewinsky.
Source: The Guardian
But news of Clinton's affair with Lewinsky got out.
In July 1998, Clinton testified over the allegations that he'd committed perjury by lying about his affair with Lewinsky. And by August, he'd admitted to having an affair with Lewinsky.
Lewinsky had also recorded conversations of her talking about the affair, and the transcripts of the conversation went public in October 1998.
On October 8, 1998, just days after the tapes were released, the House of Representatives voted for impeachment proceedings to begin against Clinton.
In a report released in September by independent counsel Kenneth Starr, there were 11 grounds for impeachment.
On December 11, 1998, the House approved three articles of impeachment along party lines — that Clinton had lied to a grand jury, that he had committed perjury by denying his relationship with Lewinsky, and that he had obstructed justice.
The next day, a fourth article was approved, which accused Clinton of abusing his power.
On December 19, 1998, the House impeached Clinton for two of the articles — perjury and obstructing justice. The votes were 228-206, and 221-212, largely along party lines.
Despite being impeached, Clinton refused to step down.
Clinton was tried by the Senate and acquitted on February 12, 1999.
His perjury charge had a vote of 55 not guilty to 45 guilty, and his obstruction of justice charge was 50 not guilty to 50 guilty. They didn't meet the two-thirds majority necessary to convict.
Senators voted largely on party lines, except for two Republicans — Sen. Susan Collins, who voted "not guilty" for both impeachment articles, and Sen. Richard Shelby, who voted "guilty" on one and "not guilty" on the other.
Clinton still had two years of his second term in office left. He spent it winning a 79-day war in Kosovo, normalizing US trade relations with China and Vietnam, and presiding over a very strong economy.
Sources: Miller Center, Clinton White House
President Donald Trump was the fourth president to face a formal impeachment investigation.
A whistleblower complaint about a July 25 phone call sparked the House investigation.
According to a memo Trump released of the call, he repeatedly pressured Ukrainian President Volodymyr Zelensky to investigate former Vice President Joe Biden and his son Hunter over baseless allegations of corruption. Trump also asked his Ukrainian counterpart to look into a bogus conspiracy theory suggesting Ukraine interfered in the 2016 US election.
The Democrats' investigation and officials' testimonies about Trump were behind closed doors in the preliminary stages.
Democratic Rep. Adam Schiff, one of the three House committee chairmen who led the inquiry, said they kept it behind closed doors so witnesses didn't coordinate their testimonies.
The Wall Street Journal's Natalie Andrews pointed out that the special counsels who investigated Nixon and Clinton both used grand juries in their probes, which does everything behind closed doors.
The investigators later turned their findings over to Congress to use in its impeachment inquiries into those presidents.
On November 13, the hearings went public, giving the nation a direct look at the key figures, the process, and the allegations. Multiple officials testified that there was quid pro quo between Trump and Ukraine.
A cascade of witness testimony since Congress launched its impeachment inquiry revealed that the Trump-Zelensky phone call was just one data point in a months-long pressure campaign spearheaded by Rudy Giuliani, Trump's personal lawyer, on behalf of the president.
Giuliani also enlisted other government officials in his efforts, including Gordon Sondland, the US ambassador to the European Union, and Kurt Volker, then the US special envoy in Ukraine.
Following the hearings, the House Intelligence Committee released a draft inquiry report on December 3. It found that Trump had conditioned "a White House meeting and military aid to Ukraine on a public announcement of investigations beneficial to his reelection campaign."
Sources: Business Insider, BBC
On December 4, the House Judiciary Committee took over. The committee was in charge of drafting the impeachment articles and laying out the case for and against impeachment. It was a highly charged and politicized affair.
Sources: Business Insider, Business Insider
On December 10, House Democrats unveiled two articles of impeachment against Trump, both relating to Ukraine. One charged him with abuse of power and the other charged him with obstructing Congress. The House Judiciary Committee vote was divided by parties — all 23 Democrats voted for it, and all 17 Republicans voted against.
House Speaker Nancy Pelosi said lawmakers were impeaching Trump to "honor our oath of office."
On December 18, the full House of Representatives impeached Trump. Both articles of impeachment passed, making him the third president in US history to be impeached.
The abuse of power article passed with a vote of 230-197, while the obstruction of Congress article passed 229-198.
Both were largely along party lines.
Two Democrats — Rep. Jeff Van Drew of New Jersey and Rep. Collin Peterson of Minnesota — voted against the first article of impeachment. Rep. Tulsi Gabbard of Hawaii, who is running for the 2020 Democratic presidential nomination, voted "present."
Amash voted in favor of the second article, while Van Drew and Peterson voted against it, as did Democratic Rep. Jared Golden of Maine. Gabbard voted "present" again.
On January 15, the full House voted to send the articles of impeachment to the Senate. There was a weeks-long delay, as House Speaker Nancy Pelosi attempted to pressure the Republican-controlled Senate into putting on a fair trial and calling new witnesses.
Source: Business Insider
Senate Majority Leader Mitch McConnell didn't cave to Pelosi's delay. He said the trial would mirror Clinton's, and witnesses would be considered at the trial's end.
Sources: Politico, Business Insider, Politico
The Senate is made up of 53 Republicans, 45 Democrats, and two independents who caucus with the Democrats. To convict Trump, 67 votes were needed to get a two-thirds majority.
Source: Business Insider
On January 22, the Senate trial arguments began. Democratic impeachment managers, including Rep. Adam Schiff and Rep. Jerry Nadler, argued to convict. Trump was defended by White House counsel Pat Cipollone and Jay Sekulow, Trump's personal attorney.
Source: Business Insider
Democrats had hoped to bring in additional witnesses to bolster the trial, but Republicans blocked the measure.
The 51-49 vote was along party lines, with only Republican Sens. Mitt Romney of Utah and Susan Collins of Maine voting in favor or calling witnesses with the Democrats.
On February 5, the Senate acquitted Trump on both charges.
For the abuse of power charge, 48 senators voted to convict Trump, including Republican Sen. Mitt Romney, who was the first senator to ever vote for the removal of a president in their own party. The other 52 Republican senators voted to acquit him.
"Corrupting an election to keep oneself in office is perhaps the most abusive and destructive violation of one's oath of office that I can imagine,"Romney said in a speech announcing his decision.
Romney joined the Republicans to vote to acquit in the obstruction of Congress charge, which passed on a 53-47 vote.
Now that the impeachment process is over, Trump will focus on his reelection campaign. According to Gallup polling, as of January 16-29, Trump's approval ratings are 49% — the best he's ever had.
Sources: Reuters, Business Insider