Beauty is in the eye of the beholder, but in court, how you create the image is about to be on trial. A fight over the hottest new fitness tool, Lululemon’s The Mirror, is now heading to the US District Court in Manhattan, as powerhouse fitness firm Nike sues Lululemon Athletica Inc for alleged patent infringement.

Lululemon purchased The Mirror in 2020 for $453 million after it became one of the most sought-after fitness devices in the US. Nike first created their large library of athletic patents for fitness tech in 1983, with patents tracking speed, time, distance and calories for runners.

Nike sued Lululemon alleging the fitness brand is using legally protected technology in their Lululemon Mirror Home Gym. The allegations by Nike that Lululemon is using technology-tracking for their Mirror reflects the evolving, multi-billion dollar home fitness boom, where users demand thousands of real-time classes, taped classes, and interactive devices that can report their results and level of participation after each class.

The lawsuit claims Lululemon’s Mirror is built with the same technology that is already protected by six utility patents. These patents, the lawsuit states, allow for the interactive features to operate when users look into the mirror to mimic their workouts. The lawsuit also alleges the technology Lululemon is using to track athletic performance, and the ability to track and record a users’ performance after a class, are also protected by patents.

Prices for the mirror at-home system, which includes a full-length mirror and app with numerous interactive real-time or taped videos for workouts at every level and type, start at $1,195 and up. There is also a monthly fee to access the workouts for the Mirror.

Nike states Lululemon’s Mirror is in violation of their “robust portfolio of patents” that has taken many years to create and grow. The company is seeking triple damages, claiming their digital sports technologies are legally protected due to their numerous patents.

Nike, in their lawsuit, states they created and built many digital, patented products that they say attract more than seventy-five million uses.

Nike’s lawsuit focuses upon patents that include brand applications, including the ability for two users in different locations to compete in real-time for a challenge; awarding users performance awards; offering easy sharing of classes for users on their social media, and instructing users based upon their heart rate (users wear a heart monitor).

Lululemon disagrees strongly with the lawsuit. In a letter sent to Nike, an attorney for Lululemon said the company rejects all of Nike’s claims, and "respects intellectual property.”

“The patents in question are overly broad and invalid,” Lululemon stated. “We are confident in our position and look forward to defending it in court.”

Since the lawsuit announcement, both Nike and Lululemon's stocks have fallen, with Nike falling 2.5 percent and Lululemon’s shares falling 4.8 percent.

Lululemon is also embroiled in another prominent lawsuit, this time with Peloton. In this case, Lululemon charges competitor Peloton with patent infringement in regard to their new line of sports bras and leggings. In that case, Peloton has already said Lululemon’s items are “too obvious” to be patented, and the case is ongoing.