During E. Jean Carroll’s civil trial, in which the writer accused former President Donald J. Trump of raping her in a department store in the mid-1990s, she testified that she had called a friend immediately afterward. On Tuesday, that friend took the witness stand.

“I am here because my friend, my good friend, who was a good person, told me something terrible that happened to her and as a result, she lost her employment and her life became very, very difficult,” said Lisa Birnbach, an author and journalist.

“I want the world to know that she is telling the truth,” Ms. Birnbach added.

Ms. Birnbach’s testimony came after Ms. Carroll wrapped up two days of cross-examination by Joseph Tacopina, Mr. Trump’s lawyer, about her allegation. Mr. Trump, who has avoided coming to court, has denied all wrongdoing.

The Accusation

Ms. Carroll said she visited Bergdorf Goodman one evening in the mid-1990s. As she was leaving through a revolving door, Mr. Trump entered and recognized her, she had testified, and persuaded her to help him shop for a gift for a female friend. She has accused the former president of going on to attack her in a dressing room in the lingerie department.

The Phone Call

Ms. Birnbach testified that Ms. Carroll called her about five to seven minutes after she said she was attacked by Mr. Trump. Ms. Birnbach said she was in her kitchen at home giving her children dinner around 6 p.m. one evening in the spring of 1996.

“She said, ‘Lisa, you’re not going to believe what happened to me,’” Ms. Birnbach testified. She said Ms. Carroll sounded “breathless, hyperventilating, emotional.”

“It sounded like she had just this surge of adrenaline,” Ms. Birnbach testified. As she listened to the story, Ms. Birnbach said she found it surprising — “I thought it was kind of nutty” — that Ms. Carroll had gone to the lingerie department with Mr. Trump, but she continued to listen.

“E. Jean said to me many times, ‘He pulled down my tights, he pulled down my tights,’ almost like she couldn’t believe it,” Ms. Birnbach said. She described how Ms. Carroll told her Mr. Trump penetrated her with his penis.

Ms. Birnbach said she went into another room and whispered to Ms. Carroll, so her children wouldn’t hear, that Ms. Carroll had been raped and that she should go to the police. Ms. Birnbach said Ms. Carroll told her she wasn’t going to the police, and she asked Ms. Birnbach to never speak of what she had told her again. Ms. Birnbach testified that they hadn’t talked about what was shared on that phone call until 2019.

Motivation in Question

During Ms. Birnbach’s cross-examination, a lawyer for Mr. Trump, W. Perry Brandt, zeroed in on her political leanings.

Ms. Birnbach, a Democrat, willingly acknowledged making campaign contributions to Hillary Clinton and Joseph R. Biden Jr.

Mr. Brandt also spent several minutes delving into a podcast Ms. Birnbach hosted from 2018 to 2021. He read excerpts from transcripts of episodes in which Ms. Birnbach called Mr. Trump “an infection like herpes that we can’t get rid of,” “Vladimir Putin’s agent” and “a narcissistic sociopath.”

After an objection from Shawn G. Crowley, one of Ms. Carroll’s lawyers, Mr. Brandt explained that his line of questioning was meant to demonstrate bias.

“Oh, really?” Judge Kaplan responded sarcastically, eliciting a rare laugh from the otherwise poker faced jurors.

Ms. Birnbach was followed on the stand by another of Ms. Carroll’s witnesses, Jessica Leeds, a former stockbroker who says that she was assaulted by Mr. Trump on an airplane in the late 1970s.