On March 9, 2020, the en banc U.S. Court of Appeals for the Ninth Circuit unanimously held in Skidmore v. Led Zeppelin that a copyright defendant’s “high degree of access” to a copyrighted work does not lower the plaintiff’s burden to show substantial similarity between the copyrighted and infringing material. In announcing this decision—and upholding the jury’s verdict that Led Zeppelin’s iconic Stairway to Heaven did not infringe a lesser-known artist’s earlier composition—the en banc court reversed its own long-standing precedent and joined four other circuits in rejecting this doctrine (sometimes called the “inverse ratio rule”). Notably, the en banc court expressed its concern that the rule had become obsolete in the digital age and that its continued application unfairly favored those who have created popular works. The Court accordingly concluded that all plaintiffs must satisfy the same standard of proof in showing that the allegedly infringing work is substantially similar to the copyrighted work—regardless of the copyrighted work’s fame.


Randy Wolfe, a guitarist in a band called Spirit, wrote the song Taurus in 1967. A copy of Taurus’s sheet music was registered with the U.S. Copyright Office later that year. In 1971, Led Zeppelin released its fourth album, which contained the well-known Stairway to Heaven. It is undisputed that Led Zeppelin and Spirit “crossed paths” several times between when Taurus was written and when Stairway was released. For example, the two bands played at the same venue on three separate occasions during that period.

In 2014, Michael Skidmore brought a copyright suit against inter alia Led Zeppelin and its members on behalf of the Randy Craig Wolfe Trust. He argued that the opening notes of Stairway infringed the first eight measures of Taurus. While the district court granted partial summary judgment on some issues, the court ultimately allowed the bulk of Skidmore’s claims to go to the jury. The district court, however, rejected Skidmore’s request to instruct the jury on the inverse ratio rule. The jury subsequently concluded that there was no infringement.


While Led Zeppelin involved—in the en banc court’s words—a wide-ranging “litany of copyright issues,” the Court’s ruling on the inverse ratio rule is perhaps its most notable contribution to copyright law.

As Judge McKeown’s decision explained, absent “direct evidence of copying,” a plaintiff must show “circumstantial[]” evidence of copying—“that the defendant had access to the plaintiff’s work and that the two works share similarities probative of copying.” For over 40 years, the Ninth Circuit has held that when a plaintiff can show that the copyright defendant had a high degree of access to the copyrighted work, the plaintiff had a lesser burden to show that there was substantial similarity between the copyrighted and allegedly infringing materials. As the en banc court noted, however, the Ninth Circuit had failed to offer a clear explanation for “how to apply the rule” in practice. To the contrary, Ninth Circuit decisions had offered “confusing” and conflicting accounts regarding the rule’s scope. In one case in the late 1980s, for example, a Ninth Circuit panel called into question the “continuing viability” of the inverse ratio rule. In contrast, a 2002 panel “pushed past the rule’s outer limits” to permit courts to find that even “[generic] similarities between [two copyrighted works] were the result of copying” where “access was not disputed.” The en banc court also noted that four other circuits—the Second, Fifth, Seventh, and Eleventh Circuits—had already rejected the inverse ratio rule, leaving the Ninth Circuit and Sixth Circuit as the only two courts to endorse it.

Faced with this legal landscape, the en banc court overruled the existing precedent that had adopted the inverse ratio rule. While the Court noted that the rule is a judge-created doctrine with no basis in the text of the Copyright Act—and that it appeared to flip the normal burden of proof in civil cases—the Court spent much of its analysis on the practical problems created by the rule.

First, the Court observed that the rule can lead to “problematic” results when “access is very high and similarity very low.” Taken to its extreme, the rule would permit liability where the defendant had “[c]omplete access” to the copyrighted work even if there were no similarities between the copyrighted and allegedly infringing material.

Second, the Court was concerned that the rule could not be applied consistently from case to case. The en banc court cited the Ninth Circuit’s own “‘checkered’” track record with applying the rule and observed that prior decisions had failed to provide any clarity regarding “how much similarity is required” when there is proof of access.

Third, the Court expressed unease that mere “access” to copyrighted material meant little in “our digitally interconnected world.” The Court suggested that, in light of the significant number of streaming services for music and video, access to copyrighted content might be “established by a trivial showing that the work is available on demand.” Relatedly, the Court worried that the rule would inequitably “benefit[]” “highly popular works”—like famous sitcoms or catchy pop hits—at the expense of less well-known media.

The Court expressed trepidation about “overruling precedent,” but it concluded that “the constellation of problems and inconsistencies in the application of the inverse ratio rule” required it to do so. While the en banc court carefully noted it was not holding that access to a copyrighted work could never serve as “circumstantial evidence of actual copying,” it emphasized that access “in no way can prove substantial similarity.”


  1. The most immediate impact of Led Zeppelin is that it lessens the circuit split over the propriety of the inverse ratio rule, leaving the Sixth Circuit as the only jurisdiction where the rule remains good law. This is significant both because the Ninth Circuit—which includes Hollywood—is an important forum for copyright cases and because Led Zeppelin may signal to other Circuits that have not yet confronted the inverse ratio rule to reject it.
  2. The decision is also notable because it acknowledges—and takes into account—the effects of the digital age on a long-standing intellectual property doctrine. While much of the Court’s rationale for overturning the inverse ratio rule would have applied prior to the existence of online streaming services, the Court seemed to place special emphasis on the practical problems that “our digitally interconnected world” has created when assessing infringement.