The lawsuit that made copyright lawyers go ape is back for another round.

Whether Naruto owns the copyright to his infamous "monkey selfie" may seem like a trivial issue, but if the 9th Circuit agrees that animals (via animal rights groups) have standing to assert so, it could have serious impacts on issues of non-human ownership in an age where artificial intelligence is no longer merely science fiction.

In 2011, wildlife photographer David Slater momentarily left his camera unattended in an Indonesian forest. Naruto, a crested macaque, snatched it up, snapped some pictures of himself and Slater later published them. PETA sued, claiming Slater infringed on Naruto's copyright as the author of the photos.

A federal judge in January dismissed the suit, finding a monkey doesn't have standing to pursue a lawsuit — and stopped short of deciding whether or not a monkey could own a copyright.

David Schwarz, who is representing Naruto through PETA, argues that just because Congress didn't expressly grant standing to animals, it doesn't mean Naruto lacked standing.

"This case presents an issue of first impression: Whether human authorship is required for protection under the Copyright Act," writes Schwarz in the appeal brief filed Thursday. (Read the brief in full here.)

Schwarz argues the district court erroneously relied on the Compendium of the U.S. Copyright Office Practices, which is not binding on the courts, and Cetacean Cmty. v. Bush, which dealt with statutes that defined who has standing, unlike the Copyright Act, which fails to define "author."

The Copyright Act, he argues, should be interpreted broadly and to specify who can be an author would be antithetical to its purpose.

"Because copyright protection exists primarily to advance society’s interest in increasing creative output, it follows that the protection under the Copyright Act does not depend on the humanity of the author, but on the originality of the work itself," Schwarz writes.

This issue, he argues, is not trivial and could impact whether "works independently created by artificially intelligent computers are entitled to copyright protection."

Schwarz says the Copyright Act makes it clear rights under it initially vest in the author of a work and a century-old Supreme Court case, Sarony, defined an author as "he to whom anything owes its origin." In this case, he says, it's clear the monkey selfies owe their origin to Naruto.

"By its silence, Congress accepted the broad constitutional notion of authorship and the judicial construction that had been in place since at least the 19th century," Schwarz writes.

He also argues that many copyrights are already held by non-human entities: corporations.

"If a work is created in an employment relationship, then 'the employer ... is considered the author,'" Schwarz writes. "This proposition is so firmly established in the jurisprudence that most copyright cases to reach the United States Supreme Court have been filed by authors who are non-humans, ranging from motion picture studios to music publishers to others."

Now, he argues, it's time for the case law to evolve.

"The fact that copyright ownership by an animal has not been previously asserted does not mean that such rights cannot be asserted," Schwarz writes. "Insofar as the issue of non-human authorship has been considered by this Court, it remains an open question. The only requirement articulated by this Court so far is that the 'author' be of this world. And Naruto certainly meets that requirement."

Attorney Andrew J. Dhuey, who reps Slater, said in a statement: "A crazy case got even crazier on appeal. The primatologist who worked with the crested macaques withdrew from the case back in May. Now it's just PETA and an Indonesian monkey it couldn't pick out of a lineup."