Former US President Donald Trump is being put on trial by lawmakers for allegedly inciting a riot at the US Capitol.
Last month Mr Trump became the first president in US history to be charged with misconduct – or impeached – twice by the lower chamber of Congress.
Republicans and Democrats in the House of Representatives voted to pass an article of impeachment that accused Mr Trump of “incitement of insurrection”.
The article alleged that Mr Trump made false allegations of election fraud and encouraged his supporters to storm Congress on 6 January.
Now a trial is being held in the upper chamber of Congress, the Senate, which will decide whether to convict or clear Mr Trump of the charge.
This is an unprecedented moment for the US, which has never put an impeached president on trial after they have left office.
How does the trial work?
The trial in the Senate is political, rather than criminal.
A vote will be held at the end of the trial to determine whether Mr Trump is guilty of the charge.
A two-thirds majority of the 100-member Senate must back a guilty verdict to convict Mr Trump.
If Mr Trump is convicted, senators could also vote to bar him from ever holding public office again.
What happens when?
The trial will open on Tuesday with a four-hour debate on whether the proceedings are unconstitutional because Trump is no longer president. A vote will then be held on the issue.
From Wednesday at noon, each side will be given 16 hours to make their arguments.
There will be an option to request a debate and a vote on whether witnesses should be called.
The Senate plans to pause the trial from Friday evening to Saturday evening for the Jewish Sabbath.
It is not clear how long the proceedings will last, but Democrats are seeking a speedy trial.
That’s because they are keen to turn their attention to the legislative agenda of Democratic President Joe Biden, who is seeking to urgently pass a Covid-19 relief plan.
What is the prosecution’s case?
Mr Trump is “personally responsible” for the riot and must be convicted, Democrats say.
In a pre-trial legal brief, they said his repeated refusal to concede the election led to an “incitement of insurrection against the republic he swore to protect”.
Mr Trump’s “statements turned his ‘wild’ rally on 6 January into a powder keg waiting to blow”, they argued.
They will use his words and footage from the riot to show that “the furious crowd” was “primed (and prepared) for violence if he lit a spark”.
“The evidence is clear,” they wrote. “When other attempts to overturn the presidential election failed, former President Trump incited an attack on the Capitol.”
Although he is no longer in office, Mr Trump “must answer comprehensively for his conduct in office from his first day in office through his last”, Democrats argued.
They have called for Mr Trump to be disqualified from ever running for office again.
What is Trump’s defence?
In their own pre-trial brief, Mr Trump’s lawyers rejected the impeachment charge against him, arguing his supporters stormed Congress of their own accord.
Mr Trump’s pre-riot remarks, his lawyers argued, did not amount to incitement.
The former president’s call to “fight” was not meant to be taken literally, the lawyers said.
“To characterise this statement alone as ‘incitement to insurrection’ is to ignore, wholesale, the remainder of Mr Trump’s speech that day, including his call for his supporters to ‘peacefully’ making their ‘voices heard,'” they said.
Moreover, FBI documents had shown that the riot was planned days in advance, the lawyers said.
In another line of argument, Mr Trump’s team rejected the case against him as unconstitutional.
They argued that, because Mr Trump is now a private citizen, he can no longer be deposed as president.
The lawyers described the trial as “political theatre” and a “brazen political act” intended to “silence a political opponent and a minority party”.
Can he be tried now he has left?
It’s never happened before, so it’s untested and the US Constitution doesn’t say.
Impeachment proceedings against President Richard Nixon were ended when he quit in 1974.
So Mr Trump could take his case to the Supreme Court, claiming his trial was unconstitutional.
Some lower ranked officials have been impeached after leaving office.
Will Trump give evidence?
That’s certainly what prosecutors wanted. Last week, they sent a letter inviting him to testify under oath “at a mutually convenient time and place”.
The prosecution team suggested that they would cite Mr Trump’s silence as further proof that their allegations were true.
Within hours, however, the former president’s lawyers had rejected the request as a publicity stunt.
They made clear he would not testify voluntarily. The prosecutors do have the power to subpoena his testimony, but that is considered unlikely.
Who will be involved in the trial?
Supreme Court Chief Justice John Roberts presided over the first impeachment trial of Mr Trump, but will not do so again.
Democratic Senator Patrick Leahy – third in the line of presidential succession – will preside over the trial instead.
Prosecuting the case will be nine House Democrats, known as the impeachment managers.
Mr Trump will be represented by two attorneys – Bruce Castor and David Schoen.
It remains unclear if he will add more people to his legal team.
All 100 US senators have been sworn in as jurors in the trial.
Could Trump be convicted in the Senate?
Democrats only hold half the 100 seats so they would require 17 Republicans to vote against someone from their own party.
That’s a high bar for a party that has largely remained publicly loyal to Mr Trump.
But 10 Republicans in the House supported impeachment and a handful of senators have indicated they are open to it.
Last week, however, 45 out of 50 Senate Republicans voted in favour of a bid to dismiss the trial.
Could Trump run for president again if convicted?
If he is convicted by the Senate, lawmakers must hold another vote to block him from running for elected office again – which he had indicated he planned to do in 2024.
This could be the biggest consequence of this impeachment.
If he is convicted, a simple majority of senators would be needed to block Mr Trump from holding “any office of honour, trust or profit under the United States”.
So 50 senators plus a casting vote from Vice-President Kamala Harris would be enough to damn Mr Trump’s hopes of political power.
This could be appealing to Republicans hoping to run for president in the future and those who want Mr Trump out of the party.
What about other benefits?
There has been talk of Mr Trump losing benefits granted to his predecessors under the 1958 Former Presidents Act, which include a pension and health insurance, and potentially a lifetime security detail at taxpayers’ expense.
However, Mr Trump is likely to keep these benefits if he is convicted after leaving office.
What was his first impeachment for again?
That was over his dealings with Ukraine, although he denied any wrongdoing.
He was accused of pressing the country’s leader to open an investigation into Mr Biden, then his emerging rival for the White House, and his son Hunter.
Mr Trump appeared to use military aid as leverage. He was impeached by the House and cleared by the then Republican-controlled Senate.
— to www.bbc.com