The alleged assault took place at a meet-and-greet for her concert in Denver, Colorado, in June 2013. David Mueller, then 51-years-old, posed for a photo with the then 23-year-old pop star and his girlfriend, when he allegedly placed his hand underneath the singers skirt and groped her.
Mueller filed a law-suit two years later in 2015, seeking $3.8 million AUD ($3 million USD) in damages for losing his job after the incident.
One month later, Taylor filed a counter-suit seeking only $1.20 AUD ($1USD) and a guilty verdict. Her team claimed: "Resolution of this Counterclaim will demonstrate that Mueller alone was the perpetrator of this humiliating and wrongful conduct targeted against Ms. Swift, and will serve as an example to other women who may resist publicly reliving similar outrageous and humiliating acts."
Here's everything you need to know about the case...
1. Mueller Claimed Taylor Accused The Wrong Person
In his initial lawsuit, Mueller said that Taylor was "confused" about who had groped her. In his filing he accused his colleague, Eddie Haskell, of sexually assaulting the singer.
Taylor's team wasted no time responding to this in their counter-suit.
"Ms. Swift knows exactly who committed the assault—it was Mueller—and she is not confused in the slightest about whether her long-term business acquaintance, Mr. Haskell, was the culprit," it read.
2. Mueller's Employer KYGO Radio Were Informed Of The Incident, Not The Police
Mueller is suing on the grounds that he lost his job over the allegations, and has questioned why his workplace was contacted but not the police.
ABC reports that a member of Swift's staff called Mueller's boss at radio station KYGO and asked that the station "take appropriate action."
Swift maintains she was assaulted but was trying to keep the matter discreet and quiet.
"The radio station was given evidence immediately after the incident. They made their independent decision,” a rep for Swift told PEOPLE at the time.
3. The Witness List Has Been Released
Andrea Swift (Taylor's mother) is listed on the names of witnesses planning to testify, and others who may be called include her photographer (who captured the photograph that allegedly shows the assault), a senior member of her management team and a bodyguard.
Mueller's girlfriend at the time, Shannon Melcher, is also expected to testify about the photgraph and her exes character.
4. The Case Is Open To The Public
32 seats will be held each day for the public, and given out on a first-come, first-serve basis. There will also be an overflow room, with passes handed out to the first 32 people in line - the public can queue as early as 6am.