Perhaps the thing I love most about intellectual property law is that it deals with the intellectual pursuits that make life worth living: music, art, literature, technology and science. No other area of law could combine what has been described as the "greatest rock song of all time" and the question of whether that song infringes the rights of the author of an earlier musical composition. That, however, is precisely the issue the U.S. Court of Appeals for the Ninth Circuit decided on March 9 in a case involving the Led Zeppelin rock masterpiece "Stairway to Heaven."

In 2014, nearly 40 years after Led Zeppelin released "Stairway," the estate of Randy Wolfe—a guitarist from the band Spirit who performed under the moniker "Randy California"—sued Led Zeppelin, its members Jimmy Page, Robert Plant and John Paul Jones, and various other music industry companies, claiming that the song had been copied from an instrumental song written in 1966 or 1967 called "Taurus."

The "Stairway" case itself involves so many issues, including the interplay of two major copyright acts in the United States, it could easily pass for a law school exam question.

If you have access to a music streaming service, you can listen to one of the various Spirit recordings of "Taurus," although listening to the recordings may give you the wrong impression. Since music recordings were not protectable under the 1909 Copyright Act (the major enactment prior to the current 1976 Act), only the musical composition itself could be claimed. In the case of "Taurus," the musical composition registered with the Copyright Office consists of only one page of music, and far less than what was ultimately included in Spirit's recordings.

After a five-day trial, which included testimony from two expert musicologists, the jury returned a verdict in favor of Led Zeppelin. According to the verdict, Led Zeppelin had access to "Taurus"—Page even admitted that he owned a copy of the Spirit album that included "Taurus"—but the songs were not substantially similar. Apparently, the jury did not believe one of the experts, who focused on three two-note sequences that appear in both compositions, instead believing the other expert who explained that any similarity in the three two-note sequences were not "musically significant" because the sequences "were preceded and followed by different notes to form distinct melodies."

Wolfe's estate appealed to the U.S. Court of Appeals for the Ninth Circuit, which first reversed the jury verdict, and then reviewing the case en banc, affirmed the jury verdict.

End of the Inverse Ratio Rule?

One of the more significant aspects of the "Stairway" case involves the Ninth Circuit's abrogation of the "inverse ratio rule," a concept that the court itself first articulated in a 1977 opinion.

Federal appeals courts are presently divided when it comes to recognizing or rejecting the inverse ratio rule, with the majority (the courts of appeals for the Second, Fifth, Seventh and Eleventh Circuits) having rejected it. Only the Sixth and Ninth Circuits had endorsed the rule.

In order to prevail in a copyright infringement action, the copyright owner must prove that the infringer copied protectable aspects of the owner's work. When dealing with certain types of copyrightable works—such as a photograph or other artwork—this concept is relatively straightforward. However, when dealing with other types of works—including musical compositions—proving infringement can be particularly challenging. In many of the more prominent cases involving musical compositions, the accused artists have defended on the grounds that they independently created their music without borrowing from the copyright owner's composition. Because of this, courts employ the access/substantial similarity test, which considers whether a defendant had access to the copyrighted work, and if so, whether the defendant's work is substantially similar to the protectable elements of the copyrighted work.

The inverse ratio rule was intended to complement the access/substantial similarity test by reducing the amount of proof of substantial similarity needed if a copyright owner could establish a high degree of access to the copyrighted work. As originally expressed by the Ninth Circuit in 1977, a showing of a high "degree of access … justified a lower standard of proof to show substantial similarity." Application of the rule, however, has been so confusing as to draw criticism.

Other circuit courts have been critical of the inverse ratio rule. The Second Circuit rejected the concept in 1961, describing it as a "superficially attractive apophthegm which upon examination confuses more than it clarifies."

William Patry, author of a copyright treatise, suggests that "the inverse ratio theory confuses fundamental principles of infringement analysis: access is relevant only in establishing the act of copying, not in establishing the degree thereof." Going further, Patry wrote that "[t]here is nothing positive that can be said about a rule that lacks any clarity at all:  trying to get a jury to both understand the rule and apply it properly is totally impossible."

With the "Stairway" decision, the Ninth Circuit has now joined the majority of appeals courts in rejecting the inverse ratio rule.

Stairway's Next Step?

Since there is still a split in the circuit courts over the viability of the inverse ratio rule, Wolfe's estate could seek to have the Supreme Court review the case. However, with the Ninth Circuit now joining the majority of circuits, it seems far more likely that the songs will close this chapter in their history.

Samuel Lewis is board certified in intellectual property law and the co-chair of copyright practice at Cozen O'Connor in Miami, Florida. He can be reached at [email protected].