Ruby Freeman, the mother of Shaye Moss and her former co-worker in the Fulton County elections office, has taken the witness stand.

Freeman introduced herself to the jury as "Lady Ruby" as questioning got underway.

Giuliani's unfounded claims about the two women prompted a deluge of threats that ultimately drove Freeman from her suburban Atlanta home, she told ABC News' Terry Moran in an exclusive interview last year.

Giuliani attorney Joseph Sibley scrutinized the credibility of the communications expert whose report on the reach of Giuliani's defamatory statements underpins the plaintiffs' request for tens of millions of dollars in damages.

Dr. Ashlee Humphreys, an expert witness for plaintiffs Ruby Freeman and Shaye Moss, fielded questions about the methodology she used to compile a report on the reputational harm that was done to the mother and daughter. Sibley sought to poke holes in that research as part of an effort to cast doubt on her findings.

"Reputation repair campaigns such as this are common," Humphreys said in response.

Sibley also highlighted Humphreys' participation as an expert witness in other cases, including in the defamation lawsuit filed against former President Trump by the writer E. Jean Carroll, and a case involving the conservative media outlet Gateway Pundit.

Noting that her past expert witness work exclusively targeted right-wing figures, Sibley asked, "Is there a reason for that?"

"No," she replied.

Communications expert Dr. Ashlee Humphreys, testifying for the plaintiffs, estimated that the cost to repair the reputations of Shaye Moss and Ruby Freeman is between $17.8 million and $47.4 million.

Humphreys said that her assessment found that Giuliani's defamatory statements about the two election workers had a "significant, negative and long-lasting" impact on Moss and Freeman's reputations.

"To repair reputational harm is not easy," Humphreys said.

A repair campaign for Moss and Freeman would include circulating statements in multiple media outlets, hiring influencers, and running media advertisements over a long period, Humphreys testified.

Dr. Ashlee Humphreys, an expert in sociology and communications, took the stand for the plaintiffs to testify about the reach of Giuliani's false election fraud claims online and on social media.

Humphreys said that prior to December 3, 2020, "there was practically no search traffic" for Ruby Freeman. After that day, Humphreys said there was a "dramatic increase over a period of months."

Humphreys said some of the search terms between December 2020 and January 2021 were "Ruby Freeman arrested," "Ruby Freeman fraud" and "Ruby Freeman FBI."

During her testimony, Humphreys walked through her analysis of the total number of times content had been displayed to uses, known as "impressions." Her impression analysis of several videos and posts by Giuliani and former President Trump included a Dec. 23, 2020, podcast in which Giuliani mentioned Moss and Freeman, which Humphreys said received between 584,855 to 807,751 impressions.

An advertising post by the Trump campaign that falsely claimed Freeman and Moss stuffed ballots in suitcases received between 8 million and 18.2 impressions, Humphreys said.

Some of the statements Humphreys said she found in her research were from Giuliani's "strategic communications plan" to challenge the election results, which included references to Moss and Freeman.

The $15.5 million to $43 million that Freeman and Moss are seeking from Giuliani reflects the emotional distress and monetary losses associated with the former mayor's defamatory comments, according to attorneys for the mother and daughter.

If the plaintiffs receive anywhere near those figures, it would mark the latest financial blow to a man who once raked in tens of millions of dollars through security consulting and speaking fees.

Judge Beryl Howell has already ordered Giuliani to pay Freeman and Moss upwards of $230,000 as a sanction for failing to comply with the discovery process of sharing information relevant to the case. In court filings over the summer, Giuliani's lawyer asked the judge if Giuliani could defer payment, citing the former mayor's "financial difficulties" as a result of fighting a slew of litigation elsewhere.

Giuliani stands to owe millions more if he loses cases brought by two voting machine companies and his own longtime personal attorney, among other legal challenges he faces. Giuliani has denied all claims.