‘Shake it Off’ singer Taylor Swift has stood her ground in a sexual assault trial against a radio host she alleges groped her bottom during a backstage meet-and-greet session in 2013.

Denver-based radio DJ David Mueller, 55, initiated the suit, claiming Ms Swift, 27, had fabricated the story to pressure his radio station KYGO to fire him, before Ms Swift countersued for assault and battery, asking for symbolic damages of $1.

On Friday US District Judge William Martinez said the pop star could not be held liable and Mr Mueller had failed to prove she personally set out to have him fired after the incident.

Ms Swift began to cry as the judge read his decision.

Mr Mueller also sued Ms Swift’s mother, Andrea, and her radio handler, Frank Bell, for $US3 million as compensation for his ruined career. These allegations will go to jurors for a verdict.

Meanwhile, the jury will still consider Ms Swift’s claim.

The former bodyguard of the singer-songwriter, Greg Dent, testified on Friday (US time) at the US District court trial in Denver, Colorado.

Under questioning from Mr Mueller’s attorney, Gabriel McFarland, Mr Dent told the court he saw Mr Mueller’s hand under Ms Swift’s skirt.

“Her skirt went up. …She jumped,” the former police officer and National Security Agency worker told the court.

Mr Dent added that Ms Swift then moved closer to Mr Mueller’s girlfriend, Shannon Melcher, who was standing on the other side of the singer for the photograph.

He told the court he was also sure Mr Mueller had been under the influence of alcohol.

“I don’t know what level. He wasn’t staggering or falling down,” he said.

During her testimony this week, Ms Swift skipped all formalities, saying Mr Mueller had subjected her to a “very long” and “horrifying” grope.

Asked by Mr McFarland whether she was critical of Mr Dent for not intervening in the alleged sexual assault, Ms Swift responded: “I’m critical of your client sticking his hand under my skirt and grabbing my ass.”

Friends and supporters of the singer have lauded the singer’s testimony.

Actress Amber Heard, who last year accused ex-husband Johnny Depp of domestic violence, tweeted that she was “proud” of Ms Swift for “standing strong”.

Proud of @taylorswift13 for her fierce & cutting testimony & her refusal to settle for being treated like property. Her example is powerful.

— Lena Dunham (@lenadunham) August 11, 2017

When Mr McFarland argued there was no visible evidence of something inappropriate happening in the photo of the incident, Ms Swift was unwavering in her case.

“Gabe, this is a photo of him with his hand up my skirt with his hand on my ass,” she said.

“You can ask me a million questions – I’m never going to say anything different. I never have said anything different.”

Mr McFarland retorted that Swift’s skirt showed no signs it had been disturbed.

“Because my ass is located in the back of my body,” Ms Swift replied.

Rolling Stone reported at one point Mr Mueller said his hand came into contact with part of the singer’s body of what “appeared to be a rib cage or rib” and her hand or arm.

Ms Swift was again, straight in her response. “He did not touch my rib, he did not touch my hand; he grabbed my bare ass.”

Asked whether there was any possibility it wasn’t Mr Mueller who groped her but someone else, she responded:  “He had a handful of my ass. I know it was him.”

On Wednesday, Ms Swift’s mother, Andrea, pointed at Mr Mueller from the witness stand and said, “He sexually assaulted my daughter, right there, that guy.

“I heard it from my daughter’s mouth. I know that it happened.”