Fresh off his decisive win in the Iowa caucuses, former President Trump was in a Manhattan courtroom on Tuesday for the start of a civil trial over a defamation lawsuit filed by author E. Jean Carroll.

Why it matters: Trump's attendance at the hearing was voluntary. He has already been found liable for defamatory remarks he made against Carroll when he denied her rape accusations in 2019, so the jury will determine how much he owes Carroll in damages.

• Tuesday's hearing marks the start of the second civil trial Trump faces stemming from a defamation claim from Carroll.
• At the end of the previous trial, a jury held Trump liable for sexual abuse and defamation and ordered him to pay Carroll $5 million in damages.

The latest: A jury of nine people was selected Tuesday afternoon before the court adjourned until 3pm EST, CNN reports.

• The jury is expected to be sworn in after the trial resumes, followed by opening statements.
• When the trial began earlier on Tuesday, Second Circuit Judge Lewis Kaplan, who is overseeing the trial, denied a request from Trump's attorney to postpone the trial's start until Thursday so that the former president would not have to decide whether to be in court or at his mother-in-law's funeral,
• It was the second time Judge Kaplan declined to postpone the trial, after Trump's lawyers previously requested a week-long delay.
• He also reiterated his previous ruling that Trump, if he intends to speak at the trial, could delay his testimony until Jan. 22.
• After jury selection began, Judge Kaplan told prospective jurors that those selected will receive additional security measures to protect them from unwanted attention and harassment.
• The judge said their identifications would remain anonymous and that personal information would not be made public or shared with the court or involved parties.

Catch up quick: The new trial is over Carroll's original 2019 defamation lawsuit against Trump.

• While in the White House, Trump mocked Carroll and claimed that she fabricated her rape accusations against him to boost her book sales. A jury found the remarks to be defamatory in the previous trial.
• The new trial also will determine the damages Trump owes after remarks he made about Carroll during a televised CNN town hall last year following the end of the first trial.

The big picture: Trump has repeatedly tried to delay or dismiss Carroll's original lawsuit.

• In his most recent attempt, he claimed he deserved presidential immunity because he was acting within the scope of his office when he accused Carroll of making up her rape accusations.
• That argument was rejected by the Department of Justice, which previously had previously defended Trump in the lawsuit.
• The U.S. Court of Appeals for the Second Circuit ruled in December that Trump waived his right to the immunity defense by not invoking it when he first responded to Carroll's original lawsuit.

The former president also filed a counter-lawsuit against Carroll, claiming she defamed him by alleging that he had raped her after the jury's verdict in the previous trial.

• The jury did not find Trump liable for rape, though it was one of the types of battery the jurors were instructed to consider by the judge.
• Trump's counter-lawsuit was thrown out by the Judge Kaplan, who ruled that, "The difference between Ms. Carroll's allegedly defamatory statements — that Mr. Trump 'raped' her as defined in the New York Penal Law — and the 'truth' — that Mr. Trump forcibly digitally penetrated Ms. Carroll — are minimal."

Zoom out: Trump, the frontrunner in the Republican primary, has repeatedly made the courtroom an extension of the campaign trail.

• He turned up multiple times at his New York civil fraud trial, including as recently as last week, when he sought to dismiss that case as a "political agenda" during closing arguments.
• He also attended oral arguments last week in his federal 2020 election interference case.

What to watch: Jury selection is scheduled this morning, and opening arguments could take place by the afternoon.

Go deeper: 31 minutes: Trump's historic Iowa victory puts America on notice

Editor's note: This story has been updated with additional details.