Mueller sued Swift, claiming she and her team falsely accused him of groping her during a photo-taking session before a 2013 concert.
Taylor Swift's attorney accused a Colorado DJ of seeking money and fame by targeting his client with a lawsuit, as the pop star sat in the Denver courtroom watching the proceedings.
On Tuesday, Mueller testified that one of his radio station bosses, Hershel Coomer, said he had met Swift earlier before the show and that "he told me that he had his hands on her butt". She says she does not know Mueller and has no incentive to target him or to fabricate a story.
Expected to take the witness stand herself later in the trial, Swift listened intently to Mueller's testimony, resting her chin in her hand.
Why is David Mueller and Taylor Swift in court?
Though several fans showed up for the trial, public interest in watching it at the downtown Denver courthouse is lower than expected, according to the Denver Post, which said that public seats to view the trial in an overflow room were handed over to the media. She is seeking a symbolic one dollar (77p) damages, saying she wants to serve as an example to other women who have been assaulted.
Mueller's suit didn't seek a specific monetary amount but an expert retained by the ex-radio host determined that almost $3 million was a fair compensation for damages. Swift, however, was described as "stoic" and politely acknowledged fans who came to support her in the courtroom gallery. He then sued Taylor for defamation while she filed a counter-claim of physical assault. Since Swift made her allegations, the white-haired plaintiff, wearing a dark suit and a black tie, his voice occasionally cracking, told the court, "I want to clear my name".
Recording artist Taylor Swift accepts the award for 'Album of the Year, ' for '1989, ' onstage at the iHeartRadio Music Awards which broadcasted live on TBS, TNT, AND TRUTV from The Forum on April 3, 2016 in Inglewood, California.
Mueller explained that he and the singer-songwriter were trying to reach around one another, and "our hands touched and our arms touched".
During Mueller's testimony, Swift listened with her chin resting in her hand.
He said Swift had been part of thousands of meet-and-greets, but had never had an incident like what happened with Mueller.
At the pre-trial deposition that took place last October, a judge ordered that Swift's evidence be made public, although her legal team successfully argued to keep an image of the encounter being made public, stating that "it is all but assured that the photograph will be shared for scandalous and prurient interests". "It's an assault", Baldridge said.
Baldridge repeatedly asked Mueller if he could grasp "any reason, incentive or motive for Miss Swift" to make up the allegation or be involved in 2 years of litigation. Court documents say it is unlikely that either side will settle.