For observers of such things, there's nothing quite so confusing or maddening as the minds that make up the minds of the U.S. federal court system on matters of intellectual property law. (Though that feeling undoubtedly spreads to other areas, depending on your interests.) Although it's the nature of the beast that not every decision be one that you agree with, one would hope that the logic used to arrive at those decisions would at least hold up to scrutiny. Even as rulings might fall against your desired outcome, you want to at least think that the most basic precepts of law still apply, even as they are interpreted in a manner less to your liking.
It's from this perspective that we enter the once-moribund copyright case against Taylor Swift and her song "Shake It Off," now reanimated thanks to a ruling in the 9th Circuit that would seem to strain credulity. At issue was a line in Swift's song mentioning that "playas gonna play" and "haters gonna hate"; truths if we've ever heard them, but also stolen from another work, according to Sean Hall and Nathaniel Butler, who brought the copyright case against the star. The two men claimed that the phrases were lifted from their song "Playas Gon' Play," although the phrases weren't exactly identical, and that was the only vague similarity in the two songs. As such, the case was pitched out of a district court as unworthy of that august institution's time, and by all reasonable consideration likely should have joined the scrapheap of terrible and ill-advised copyright suits.
But the fates must have a soft spot for lousy lawsuits, because the matter was sent back to the district court by the panel of 9th Circuit Court judges. The judges' argument for the revival rests on the idea that the idea of copyright protection is "one of fact, not of law," and inveighing Oliver Wendell Holmes' exhortation that judges not be the arbiters of what does or does not have artistic creativity and merit. If you think that point is separate and apart from the question of what is eligible for copyright protection, you wouldn't be alone in that thinking; Techdirt even notes that short phrases are, per the rules of the U.S. Copyright Office, ineligible for copyright.
As a non-lawyer myself, I can't speculate as to why the 9th Circuit would arrive at such a ruling that would seem to go against the basic tenants of copyright law that even an interested layperson accepts as given. The only explanation that makes sense —that makes the disposition of the case make sense— is that the judges are themselves Katy Perry fans.