It’s been widely reported in the news and on this blog—a jury in a Federal copyright infringement case has reached a verdict favoring legendary rock band Led Zeppelin, finding that it did not plagiarize the iconic guitar riff from the band’s hit song “Stairway to Heaven.” However, almost nobody is talking about the law behind that verdict.

In the law of copyright, just how similar is too similar when it comes to music? We all know that in the world of popular music, musical styles come and go. There is no question that when a certain “sound” becomes popular, that sound will influence and be echoed by other artists. However, by what standard does the law judge if a musical work is too similar to a prior work?

Among the things that must be proven in any case of infringement of a musical work protected by copyright is that the alleged infringer copied protected elements of the original work. Swirsky v. Carey (9th Cir. 2004) 376 F.3d 841, 844. That may be done by showing that the new work is “substantially similar” to the original work. Two tests are employed by the courts in the 9th Circuit, an “objective extrinsic test” and a “subjective intrinsic test.” Id.

The objective extrinsic test turns on “whether two works share a similarity of ideas and expression as measured by external, objective criteria.” Id. This requires an “analytical dissection,” basically breaking the work down into particular components and comparing them for similarities. Any infringement case involving musical works will involve musicology experts opining on matters such as rhythm, tempo, pitch, chord changes, lyrics, and other stylistic and compositional elements. The courts have observed that there is no “uniform set of factors to be used” in judging the compositional similarity of two works. Swirsky v. Carey, supra, 376 F.3d 841 at 849.

The subjective intrinsic test turns on “whether the ordinary, reasonable person would find the total concept and feel of the works to be substantially similar.” Three Boys Music Corp. v. Bolton (9th Cir. 2000) 212 F.3d 477, 485, quoting Pasillas v. McDonald’s Corp. (9th Cir.1991) 927 F.2d 440, 442.

Another relevant consideration in the Ninth Circuit’s infringement jurisprudence is what is known as the “inverse-ratio rule.” Under that rule, the greater the showing made as to the actual access to the original work by the alleged infringer, the less rigorous the showing of substantial similarity must be. Three Boys Music Corp. v. Bolton, supra, 212 F.3d at 486. In other words, if the evidence were to show that a songwriter had seen the original work performed just before writing his or her hit song that supposedly infringed that original work, then less evidence is required to prove the substantial similarity between the two works. In the Stairway to Heaven case, the plaintiff offered evidence that Led Zeppelin and the plaintiff’s band Spirit had toured together and  Spirit had performed the song that included the opening guitar section that Led Zeppelin had allegedly copied. Access aside, the jury concluded that the works were not sufficiently similar.

Accordingly, infringement of a musical work involves a complicated analysis under the law. That analysis can turn on circumstantial evidence as to how the songs came about, as well pure musical theory. So all that glitters is not necessarily gold in the law of music infringement.

In Robert Plant’s world, all that glitters is not gold, and all that sounds like another artist’s work is not stolen from that artist. Fortunately for Plant and his Led Zeppelin bandmates, a Los Angeles jury agreed. That jury found on Thursday that the estate of Randy Craig Wolfe, the lead guitar player for a Zeppelin contemporary, Spirit, had not proved that the iconic opening guitar riff to “Stairway to Heaven” was lifted from Spirit’s “Taurus.”

The Lawsuit

The suit alleged that Led Zeppelin copied parts of Stairway from Spirit’s single, “Taurus.” Wolfe, who wrote Taurus, stated prior to his death that “it was a rip-off” of his music. His estate now seeks damages and writing credit for Wolfe.

After listening to Taurus,  it is safe to say that even casual fans of Zeppelin’s work can likely identify the chords that Wolfe believed Zeppelin to have “ripped off.” There is also little question that Page and Plant had access to Spirit’s work. Between 1968 and 1969, the two bands played five shows together. Spirit played “Taurus” at each of those shows.

The Jury’s Findings

Indeed, the jury expressly found that members of Led Zeppelin had heard “Taurus.” Nonetheless, a half-an-hour after listening to both songs one last time, the jurors issued their verdict that the songs lacked substantial similarity in their extrinsic elements.

Wolfe’s estate has already vowed to appeal the decision, perhaps based on U.S. District Judge R. Gary Klausner’s refusal to allow the jury to hear alternative versions of Spirit playing “Taurus.” Judge Klausner ruled that the jury should not hear these recordings because Wolfe’s copyright extended only to the sheet music filed with the U.S. Copyright Office.

Vindication of Oft-Accused Artists

Thursday’s verdict comes as something of a vindication for a band that has repeatedly faced copyright infringement claims and accusations. The opening lyrics for “Whole Lotta Love” are remarkably similar to the final verse of the Muddy Waters song “You Need Love.” “The Lemon Song” contains a number of lyrics similar to Howlin’ Wolf’s “Killing Floor,” a song Zeppelin played routinely during the same 1968-1969 American tour in which it opened five shows for Spirit. Copyright infringement suits related to both of these works, as well as several others, resulted in out-of-court settlements and song-writing credit given to the plaintiff. “Stairway” is the first song over which the band has litigated infringement claims through trial.

[Note: This post was authored by Jason Horst.]