In the 1980s, Andy Warhol created an illustration of the musician Prince, which drew heavily from an existing image by photographer Lynn Goldsmith.

Now, four decades later, the Supreme Court has ruled that the Pop artist infringed on Goldsmith’s copyright. Experts say that the case has complex implications for the ever-shifting boundaries of copyright infringement and fair-use law.

Seven out of the nine Supreme Court justices ruled against Warhol’s estate, which argued that the portrait in question should be considered the work of Warhol alone.

“To hold otherwise would potentially authorize a range of commercial copying of photographs, to be used for purposes that are substantially the same as those of the originals,” wrote Justice Sonia Sotomayor in the majority opinion.

The two dissenting justices, Elena Kagan and John Roberts, argue that this ruling could stifle the creativity of artists who want to riff off of copyrighted material.

“It will impede new art and music and literature,” wrote Kagan. “It will give the expression of new ideas and the attainment of new knowledge. It will make our world poorer.”

The saga began in 1981, when Newsweek commissioned Goldsmith to photograph Prince. in 1984, VanityFair hired Warhol to create an illustration of the musician for an article; the magazine also paid Goldsmith a one-time fee of $400 so that Warhol could use one of her photos as a reference point.

After Prince’s death in 2016, Condé Nast (which operates VanityFair) used Warhol’s art for a tribute to the musicians. The company paid Warhol’s estate for the right to use the image, reasoning that this version of the work was Warhol’s.

Goldsmith, however, had only authorized Condé Nast to use the image once.

The legal battle revolves around a divisive question: After Warhol altered the image, did it belong only to him, or should Goldsmith retain some degree of control?

The court’s decision depends on how the image was used. In this case, wrote the justices, the commercial nature of the Prince portraits means that the images aren’t covered by fair-use law.

Still, the ruling stipulated that certain other Warhol pieces—such as his famous depiction of Campbell’s soup cans—should be viewed in a different light. Sotomayor wrote, “The purpose of Campbell’s logo is to advertise soup. Warhol’s canvases do not share that purpose. Rather, the Soup Cans series uses Campbell’s copyrighted work for an artistic commentary on consumerism, a purpose that is orthogonal to advertising soup.”

Michael W. Carroll, a scholar of intellectual property law at American University Washington College of Law, tells the New York Times‘ Matt Stevens that this distinction is critical. “It was the licensing use, not the creative use, that was the issue,” he said.

Warhol built his career by transforming the photos of others. For example, his 1964 Marilyn Monroe portraits are based on a publicity photo for the film Niagara (1953); last year, one of those portraits, Shot Sage Blue Marilyn, became the most expensive 20th-century American artwork ever sold. Other images from popular culture—from Coca-Cola bottles to Disney characters—also served as source material.

Reactions to the Supreme Court ruling were mixed. Noah Feldman, a scholar of law at Harvard, writes in Bloomberg that the decision helps artists but harms creativity.

“The upshot is that little-guy artists win, because they now have more rights than they had before to claim credit for works reused by others,” he wrote. “But art as a whole loses, because the decision restricts how artists generate creativity by sampling and remixing existing works.”

Carroll tells the Times that the ruling leaves a lot of room for conflicting interpretations, and the legal battle has only just begun.

“Is it really just about competitive licensing use, or is it more broadly about creating derivative works?” he added. “I think what you’ll see is lower courts reading it each way, and then eventually this issue is going to find its way back to the Supreme Court.”