International pop superstar Katy Perry has had a court win in her long-running trademark battle with an Australian fashion designer after her decade-old Prism tour.

The US singer, whose real name is Katheryn Hudson, today successfully appealed 2023 Federal Court findings that her firm Kitty Purry engaged in trademark infringement during the 2014 Australian tour.

Fashion designer Katie Jane Taylor sued Perry in October 2019, more than 10 years after the performer behind hits like Firework, Roar and Dark Horse started selling merchandise, including clothing, under her own name.

The designer had sold her own line of clothing under the Katie Perry label since 2007 after becoming inspired by a trip to Italy.

Today, three appeal judges unanimously overturned Justice Brigitte Markovic’s findings and ordered that Taylor’s trademark be deregistered.

They described the case as an “unfortunate one” in which two enterprising women in different countries had adopted their names as a trademark.

“Both women put blood, sweat and tears into developing their businesses,” they wrote.

“As the fame of one grew internationally, the other became aware of her namesake and filed a trademark application.”

Perry used her name as a trademark in good faith during the 2014 Prism tour and had been doing so five years before Taylor launched her own business, the judges noted.

The pop singer’s name was also used honestly on clothing and other merchandise sold in Australia, the court found.

In May 2009, after becoming aware of Taylor’s application to register the Katie Perry trademark, the superstar told her talent agent Steven Jensen to “keep me outta it entirely”.

“I wouldn’t have even bothered with this (if) mtv hadn’t picked up this silliness,” she wrote in an email.

The Katie Perry trademark had been applied for when Taylor already knew of the singer’s reputation, the judges found.

It was deregistered today after the Full Court ruled it was deceptively similar to the Katy Perry brand and was likely to cause confusion amongst consumers.

While die-hard fans would notice the slight differences in spelling, the ordinary consumer would wonder whether clothing sold by the local designer was associated with the US pop star, the court found.

In a statement, Taylor said she was devastated and heartbroken by the decision.

“This case proves a trademark isn’t worth the paper it’s printed on,” she said.

“My fashion label has been a dream of mine since I was 11 years old and now that dream that I have worked so hard for, since 2006, has been taken away.”

She said she would take time with her legal team to consider the judgment and what next steps were available.

Perry declined to comment when contacted through her lawyers.

She will tour Australia for the first time in six years in June after making a brief visit to the country in September to perform at the AFL grand final.