Top U.S. diplomat in Ukraine William Taylor, left, and Foreign Service officer George Kent are sworn in before the House Intelligence Committee during the first public impeachment hearing.
AP/Jim Lo Scalzo/Pool Photo
The first day of public impeachment testimony was defined, in part, by strongly worded statements from Representatives Adam Schiff and Devin Nunes.
Trump has broken a lot of norms.
AP Photo/Seth Wenig
Norms are perceptions or beliefs about what we understand the rules for acceptable behavior to be. Trump's impeachment could help restore some of them.
President Donald Trump meets with British Prime Minister Boris Johnson at the United Nations General Assembly in September 2019. Both men have put the rule of law in their crosshairs.
(AP Photo/Evan Vucci)
Authoritative statements by esteemed officials that the rule of law has been violated no longer have political consequences. Scandals that would have ended careers only a few years ago barely register.
Ukrainians don’t agree on how their president should have handled Trump’s request.
Trump's attempt to co-opt Ukraine's precarious position with Russia worsens existing divides inside Ukraine and weakens US influence abroad.
Sen. Susan Collins is among the senators who have chosen to stay quiet about impeachment so far.
AP Photo/J. Scott Applewhite
No written law or rule requires the senators to remain silent on the issues. But it's probably a good idea, and a promising sign of fairness.
The whistleblower: in Trump’s sights.
A former British whistleblower on the damage done when those who come forward with the truth are stigmatised.
Dr. Mona Hanna-Attisha, right, on Capitol Hill in Washington, in February . 2016.
AP Photo/Andrew Harnik
Whistleblowers may stop bad behavior and protect others from harm.
Trump takes the stage at a Make America Great Again rally in April 2019 in Green Bay, Wis. Trump and his defenders claim the ongoing impeachment process is a coup. But is it Trump who’s truly engaging in a coup?
AP Photo/Mike Roemer
Since the election of Donald Trump, the United States has been experiencing a slow-moving coup that is still in the process of toppling American democratic institutions.
US Speaker of the House Nancy Pelosi speaks during her weekly press briefing on October 8, 2019. She accused the White House of an “unlawful attempt to hide the facts” after it ruled out cooperating with an impeachment probe of President Donald Trump.
The impeachment investigation of US president Donald Trump has formally started, but much has changed since 1974, when Richard Nixon was forced out of office.
Kentucky Republican Mitch McConnell, the senate majority leader, has a lot of power.
AP Photo/Timothy D. Easley
Senate Majority Leader Mitch McConnell is known as a master of Senate rules. If the House impeaches President Trump, what could he do to influence the process – and outcome – of a trial?
Senator Chuck Schumer holds up the White House transcript of a call between President Donald Trump and the president of Ukraine.
AP Photo/Jacquelyn Martin
Members of Congress factor what the public thinks into their decisions. But it's difficult to measure what the public is really thinking.
Refusing to cooperate.
Jim Lo Scalzo/EPA
Are Republican leaders overestimating the extent to which the public wants them to defend Donald Trump?
While there has only been a modest drop in Trump’s ratings, support for impeachment has risen sharply.
AAP/EPA/Jim Lo Scalzo
Meanwhile, the polls indicated that support for impeachment has shifted markedly, with most Americans now supporting it.
Trump’s approval rating has a lower ceiling and higher floor than that of past presidents.
Investigations often damage the president's approval rating, particularly if the inquiry drags on for a long time. But that may not matter to a historically unpopular president like Trump.
As the impeachment inquiry gathers pace in the US, Donald Trump is likely to keep doubling down on his opponents.
As the impeachment inquiry gathers pace, both sides seem to be digging in. What happens in the inquiry in the next few months will have a huge impact on the 2020 presidential election.
President Richard Nixon, left, and President Donald Trump, right.
AP//Frank C. Curtin; REUTERS/Jonathan Ernst
President Trump solicited foreign help for his presidential campaign. So did presidential candidate Richard Nixon. The difference, writes scholar Ken Hughes, is that Nixon was more skilled at it.
If he’s kicked out, could he come back?
AP Photo/Evan Vucci
A little-known provision of the Constitution might allow Trump to be reelected president in 2020 even if he is removed from office through the impeachment process.
Blowing the whistle carries major risks.
In many instances, whistleblowers find the abusive power they have revealed turned against them, both ending their careers and harming their personal lives.
Donald Trump and Rudy Giuliani in late November 2016, after Trump won the presidential election.
A former congressional staffer says withholding damning evidence from Congress and using civilians to carry out presidential or intelligence agency agendas links the Ukraine crisis to other scandals.
Ukraine Presidential Press Service/EPA
How Ukraine has reacted to controversy over a phone call between its President Volodymyr Zelenskiy and Donald Trump.