A legal contest over alleged copyright infringement in Robin Thicke’s “Blurred Lines” became a referendum on the singer’s character. Photograph by Charles Sykes / Invision / AP

There was far more Schadenfreude than sorrow when, on Tuesday, Robin Thicke and his colleagues were defeated in a legal contest over copyright by the Marvin Gaye estate. The charge: that Thicke’s 2013 hit “Blurred Lines” lifted from a 1977 single by Gaye. Gaye is widely revered, while Thicke, throughout the trial, came across as enormously unappealing. He now says that he did not actually write “Blurred Lines,” his most famous song—which would mean that he lied about this to Oprah Winfrey, a cardinal sin in contemporary America. Many find the song’s lyrics and its music video morally objectionable, and it does not help that Mr. Thicke, with his aviators and swaggering demeanor, seems to be borrowing from another act: the old “Saturday Night Live” skit “The Roxbury Guys.”

The idea that Thicke—or, more precisely, Pharrell Williams, his collaborator, who actually wrote the song—stole “Blurred Lines” from Gaye completes the "jackass" narrative nicely. Nonetheless, a serious error has been made: the judge overseeing the case should never have let the case go before a jury. The ruling against Thicke was a mistake, and it should, and likely will, be reversed on appeal.

There is no question that Pharrell was inspired by Gaye and borrowed from him; he has freely admitted as much. But, by that standard, every composer would be a lawbreaker. The question is not whether Pharrell borrowed from Gaye but whether Gaye owned the thing that was borrowed. And this is where the case falls apart. For it was not any actual sequence of notes that Pharrell borrowed, but rather the general style of Gaye’s songs. That is why “Blurred Lines” sounds very much like a Marvin Gaye song. But to say that something “sounds like” something else does not amount to copyright infringement.

This is not like the rapper Vanilla Ice using the opening riff from “Under Pressure,” by Queen and David Bowie, in his hit “Ice Ice Baby,” adding just a single note. That 1990 case involved the kind of literal copying that the law clearly prohibits. In contrast, as Pharrell’s counsel pointed out, “Blurred Lines” actually has more notes in common with the 1966 Lee Dorsey song “Working in the Coal Mine” than with Gaye’s “Got to Give It Up,” which Pharrell is accused of copying.

There are those who, perhaps after listening to a popular mashup of the two songs, maintain that they seem similar, note sequences be damned. But, even accepting that some of Gaye’s style elements—such as the male falsetto and the use of cowbell—may, in combination, be distinctive enough to warrant legal protection, there remains a technical problem that will likely get this verdict thrown out. The Gaye estate’s copyright covers only the notes of his song (the composition), and not the way it was played (the sound recording). These copyrights are separate. Gaye reportedly submitted sheet music for “Got to Give It Up” to the U.S. Copyright Office in 1977, thus registering his copyright of the composition. But he appears not to have complied with the formalities necessary to obtain copyright of the recording.

With a broader copyright, Gaye’s estate would have a stronger claim to owning some of his particularly distinctive style choices. But, given that the copyright covers only the notes and Pharell did not borrow any note sequences, the judge was legally obliged to throw out the case.

His failure to do so has led not only to an excessive fine (more than $7.3 million) but also to the possibility of a federal ban on the playing of “Blurred Lines”—a potentiality that makes the stakes of this case clear. Copyright is ultimately subject to the limits imposed by the First Amendment; the borrowing of styles is too important an expressive freedom to be subject to federally enforced censorship.

Consider the sheer number of creators who would be affected if such rulings were levied more widely. Everyone knows that the Rolling Stones borrowed their style from Chuck Berry and other rhythm-and-blues artists. Rush’s first album sounds a lot like Led Zeppelin—who copied Robert Johnson, among others. Nor is this true only in musical composition. Georges Braque and Pablo Picasso borrowed ideas from Paul Cézanne to develop Cubism, for instance, a style that was, in turn, copied by numerous others. There are hundreds of other examples. To suggest that this verdict will encourage better songwriting is to misunderstand the history of the arts. The freedom of artists and other creators to borrow from each other is connected with the principle that ideas cannot be copyrighted, a notion that is essential to free speech and artistic expression.

The Gaye estate’s victory was an accomplished piece of lawyering, for which its counsel deserves credit. The estate’s lawyers, taking advantage of the fact that Gaye is considerably more popular and respected than Thicke, made a dispute between two groups of wealthy people seem like a battle between good and evil. Rather than focussing on what Gaye’s estate actually owned, the trial became a referendum on Thicke’s character. As for that, the verdict was already clear.