Donald Trump faces an unprecedented second impeachment trial.
Donald Trump's defence is off to a shaky start at his impeachent trial in the US Senate, with experts panning the performance of lawyer Bruce Castor.
His opening argument has baffled commentators and legal experts - including Trump supporters. Here, for example, is constitutional lawyer Alan Dershowitz, appearing on the pro-Trump network Newsmax.
"What are you making of Bruce Castor's argument so far? Where is he heading with this?" the host asked him.
"There is no argument. I have no idea what he's doing. I have no idea why he's saying what he's saying," Dershowitz said.
"This, just – after all kinds of very strong presentations on behalf of the House managers, and the emotional case by Congressman Raskin – you get up there and you respond.
"I just don't understand it. Maybe he'll bring it home, but right now, it does not appear to me to be effective advocacy. He may know the senators better than I do, maybe they want to be buttered up, maybe they want to be told what great people they are.
"Boy, it's not the kind of argument I would have made, I'll tell you that."
Rep. Raskin's opening impeachment trial statement: "Their argument is that if you commit an impeachable offense in your last few weeks in office, you do it with constitutional impunity." pic.twitter.com/lIrRiu36IF
Trump's historic second impeachment trial opened early this morning (NZ time) with graphic video of the deadly attack on Congress and the defeated former president whipping up a rally crowd — "We're going to walk down to the Capitol!" — as he encouraged a futile fight for his presidency.
The lead House prosecutor told senators the case would present "cold, hard facts" against Trump, who is charged with inciting the siege of the Capitol to overturn the election he lost to Democrat Joe Biden.
Senators sitting as jurors, many who fled for safety that day, watched the jarring video that showed the chaotic scene, rioters pushing past police to storm the halls, Trump flags waving.
Trump is the first president to face impeachment charges after leaving office and the first to be twice impeached. The January 6 Capitol siege stunned the world as rioters stormed the building to try to stop the certification of Biden's victory, a domestic attack on the nation's seat of government unlike any in its history. Five people died.
Trump's lawyers are insisting that he is not guilty of the sole charge of "incitement of insurrection", his fiery words just a figure of speech as he encouraged a rally crowd to "fight like hell" for his presidency.
The defeated former president is charged by the House with inciting the deadly mob attack on the Capitol to overturn the election in what prosecutors call the "most grievous constitutional crime".
How does the trial work?
As laid out by the Constitution, the House votes to impeach and the Senate then holds a trial. A two-thirds vote is needed for a conviction.
The House appointed nine impeachment managers who will present the case against Trump on the Senate floor. Trump's defence team will have equal time to argue against conviction.
The chief justice of the United States normally presides over the trial of a president, but because Trump has left office, the presiding officer will be Democrat Senator Patrick Leahy, who is the ceremonial head of the Senate as the longest-serving member of the majority party.
Once the senators reach a final vote on the impeachment charge, each lawmaker will stand up and cast their vote: guilty or not guilty.
How long will the trial last?
Likely more than a week. The agreement between Senate leaders provides for up to 16 hours for prosecutors and the defence to make their arguments, with no more than eight hours of arguments per day. Later, there will be time for senators to ask questions, and there could be additional procedural votes.
Under the agreement, the trial will open with four hours of debate on whether it is constitutional. The Senate will then vote on whether to dismiss the charge against Trump. If that vote fails, as expected, the House managers will begin their arguments Wednesday (Thursday NZ time) and continue into the next day.
Trump's lawyers are likely to begin their arguments Friday and finish Saturday. That almost certainly means a final vote on Trump's conviction won't happen until next week.
Trump's first impeachment trial, in which he was acquitted on charges that he abused power by pressuring Ukraine to investigate now-President Joe Biden, lasted almost three weeks. But this one is expected to be shorter, as the case is less complicated and the senators know many of the details already, having been in the Capitol during the insurrection.
Unlikely witnesses will be called
The House prosecutors will argue there is no "January exception" to a president's actions just before he leaves office and that the trial has ample precedent, according to aides familiar with the arguments and granted anonymity to discuss them before the trial.
It appears unlikely that the House prosecutors will call witnesses, in part because the senators sworn as jurors, forced to flee for safety, will be presented with graphic videos recorded that day. At his Mar-a-Lago club in Florida, Trump has declined a request to testify.
Unprecedented second impeachment
The first president to face charges after leaving office and the first to be twice impeached for high crimes and misdemeanours while in office, Trump remains a challenge to the nation's civic norms and traditions even in defeat. Security remains extremely tight at the Capitol.
Acquittal is likely, but the trial will test the nation's attitude towards his brand of presidential power, the Democrats' resolve in pursuing him, and the loyalty of Trump's Republican allies defending him.
White House press secretary Jen Psaki said Monday that Biden will be busy with the business of the presidency and won't spend much time watching the televised proceedings. "He'll leave it to his former colleagues in the Senate," she said.
A presidential impeachment trial has been conducted only three times before, leading to acquittals for Andrew Johnson, Bill Clinton and then Trump last year.