This week, a jury in Manhattan will decide how much money Donald Trump should pay to a writer who said he raped her.
E Jean Carroll wants $10 million because she says Donald Trump’s comments about her and the accusations hurt her.
Last year, a jury in New York decided that he attacked and lied about Ms Carroll, and they gave her $5 million.
Mr Trump says he did nothing wrong and is asking for the decision to be reviewed.
He went to the courthouse on Tuesday morning to join the group of people who are chosen to decide the outcome of a trial.
He arrived just a few hours after giving a speech in Iowa where he won the first Republican presidential nomination contest.
This court case is about Mr. Trump saying he didn’t rape Ms. Carroll when she first talked about it in a New York magazine a little over three years ago.
At that time, Mr Trump said her story was not true at all. He said he never heard of Ms. Carroll and she made up the story to sell her book.
This case is different from a previous trial in May where a New York jury decided that the former president hurt Ms. Carroll in a sexual way, but did not do anything wrong when she said he raped her in a dressing room in the 1990s.
The jury decided that Mr. Trump was responsible for making false and damaging statements about the magazine writer.
In September, Judge Lewis Kaplan decided that the second trial against Mr. Trump will only focus on deciding how much money should be paid for harm caused.
The judge told the ex-president to be careful about what he says in court.
He is not allowed to say or show anything suggesting that he didn’t sexually assault Ms Carroll, that she made up the assault, or that she had a reason to lie.
Ms Carroll’s lawyer, Roberta Kaplan, who is not related to Judge Kaplan, said that Mr. Trump will try to create confusion with his testimony. She wants him to promise, in court, that he knows what he can and cannot say.
“Mr Trump may have many reasons to want to turn this trial into a circus, for his own personal or political gain,” she wrote in a memo to Judge Kaplan.
Mr Trump’s lawyer, Alina Habba, said that the former president knows about the court’s decision and the rules for his testimony.
The ex-president is in trouble with the law for trying to change the election results and for how he handled secret documents.