Climbing Down: Skidmore v. Led Zeppelin and the End of the Inverse Ratio Rule

The en banc Ninth Circuit's decision upholding the 'Stairway to Heaven' verdict, confining old compositions to their deposit copies, and abolishing the inverse ratio rule.

Skidmore v. Led Zeppelin, Nos. 16-56057 & 16-56287 (9th Cir. Mar. 9, 2020) (en banc), is the rare music copyright decision that reshaped doctrine while reaching a result the public found anticlimactic: Led Zeppelin won, again. The trustee for the late Randy Wolfe—“Randy California” of the band Spirit—claimed that the opening of “Stairway to Heaven” (1971) infringed Spirit’s instrumental “Taurus” (1967). A jury had said no. The en banc Ninth Circuit affirmed, and in doing so confined older compositions to their Copyright Office deposit copies, reaffirmed the limits of “thin” protection for common musical building blocks, and abolished the long-criticized “inverse ratio rule.”

At a glance

Matter: Skidmore v. Led Zeppelin, Nos. 16-56057 & 16-56287 (en banc)
Forum: U.S. Court of Appeals for the Ninth Circuit, sitting en banc (on appeal from the Central District of California, Judge R. Gary Klausner)
Decided: March 9, 2020 (Supreme Court denied certiorari later in 2020)
The works: Spirit’s “Taurus” (registered 1967) and Led Zeppelin’s “Stairway to Heaven” (1971)
The disputed material: A descending chromatic bass line under an A-minor chord—a centuries-old musical commonplace
Holdings: The 1909 Act governs; the copyright is limited to the deposit copy (a one-page lead sheet); the inverse ratio rule is abolished; the “selection and arrangement” theory was properly handled
Result: Jury verdict of non-infringement affirmed

Why the recording never reached the jury

The most consequential ruling is also the most technical. Because “Taurus” was registered in 1967, the 1909 Copyright Act governs the scope of its protection—and under that Act, the protected work is what the author deposited with the Copyright Office. For “Taurus,” the deposit was a single-page lead sheet containing the basic notation, not the lush studio recording listeners associate with the song. The 1909 Act did not even extend federal copyright to sound recordings.

That meant the jury could not be played the “Taurus” recording as proof of substantial similarity. Skidmore argued this was reversible error—that the recording captured the true expression and the jury should hear how alike the songs sound. The en banc court disagreed: the deposit copy defines the protectable composition for a 1909-Act work, so the comparison must run between “Stairway” and the lead sheet, not the master. The recording could be relevant to other issues, such as access, but not to the similarity of the protected composition itself. This holding gives defendants litigating vintage songs a powerful structural argument: strip the case down to the often-sparse notation on file.

Thin protection for common building blocks

The substance of the dispute was a descending chromatic line—notes moving down by half-steps—played beneath a minor chord. Skidmore’s expert characterized it as a distinctive, protectable sequence; Led Zeppelin’s experts called it one of the oldest tricks in Western music, found in works from Bach to countless pop songs. The en banc court did not have to resolve the musicology because the jury, properly instructed, had already found the works not substantially similar. But the opinion reinforced a foundational principle: individual musical elements—a scale, a common chord progression, a chromatic descent—are building blocks in the public domain, and copyright protects only an author’s original selection, coordination, and arrangement of such elements.

Skidmore pressed exactly that selection-and-arrangement theory, arguing that even if each element was unprotectable, “Taurus” combined them in an original way. The court accepted the theory’s legitimacy but held that the district court had not erred in its handling of it; the jury instructions adequately conveyed the law, and the trial court was not required to give a specific “selection and arrangement” instruction the plaintiff belatedly wanted. The decision thus illustrates the double edge of thin copyright: a plaintiff may protect an original arrangement of commonplaces, but must prove a virtually identical taking of that arrangement, a demanding standard the jury found unmet.

Burying the inverse ratio rule

The en banc court used the case to abolish a doctrine that had distorted Ninth Circuit infringement analysis for decades: the inverse ratio rule, which held that a strong showing of access to the plaintiff’s work lowered the standard of proof for substantial similarity. The logic had always been shaky—access and similarity are conceptually distinct, and the rule effectively let a plaintiff prove less about the actual works by proving more about exposure.

The court catalogued the rule’s incoherence and inconsistent application, noted that most circuits had rejected it, and overruled its own precedents endorsing it. Access, the court explained, is a proxy for the factual question of copying; it cannot substitute for the legal question whether enough protectable expression was actually taken to make the works substantially similar. In the streaming era, where virtually any song is universally accessible, the rule had become especially perverse: ubiquity would automatically dilute the similarity required. Eliminating it tightens the analysis and benefits defendants facing claims built on fame and exposure rather than genuine resemblance.

Open questions

Does the deposit-copy rule unfairly shrink old songs? Composers of the 1909-Act era often deposited skeletal lead sheets; tying protection to that notation may understate the creativity actually fixed in the recording. The fairness of that bargain remains debated.
How thin is too thin? The line between an unprotectable commonplace and an original arrangement of commonplaces is irreducibly fact-bound, leaving substantial uncertainty for both plaintiffs and defendants.
Will other circuits formally follow on the inverse ratio rule? The Ninth Circuit’s abolition aligns it with the majority view, but the doctrine’s residue lingers in older cases and jury instincts about access.
What is the role of expert musicology now? With recordings excluded for 1909-Act compositions, the battle turns on competing expert readings of sparse notation—an arena prone to advocacy dressed as analysis.

Implications

For vintage compositions, the deposit copy is the case. Litigants must obtain and scrutinize the Copyright Office deposit; the famous recording may be legally irrelevant to similarity.
Building blocks stay free. Scales, common progressions, and chromatic lines remain unprotectable; only original arrangements qualify, and only against near-identical copying.
Fame no longer lowers the bar. With the inverse ratio rule gone, plaintiffs cannot leverage a defendant’s exposure to ease their similarity burden.
Defendants gain structural tools. Confining the comparison to notation and demanding virtual identity for thin works are now potent defenses in song-similarity suits.
The Ninth Circuit signaled restraint. Read alongside the “Blurred Lines” anxiety, Skidmore pushes back against expansive music copyright claims built on feel or fame.

Frequently asked questions

Why couldn’t the jury hear the “Taurus” recording? Because “Taurus” is governed by the 1909 Copyright Act, its protected work is the composition as deposited with the Copyright Office—a one-page lead sheet. The 1909 Act did not protect sound recordings, so the comparison for substantial similarity ran between “Stairway to Heaven” and the notation, not the Spirit master.

What was the “inverse ratio rule” and why did the court abolish it? It held that stronger evidence of access to the plaintiff’s work lowered the degree of similarity a plaintiff had to prove. The en banc court found the rule logically unsound and unevenly applied—access and similarity are distinct—and overruled it, especially given that in the digital age nearly every work is widely accessible.

Does Skidmore mean common musical phrases can never be protected? Individual commonplaces—a chromatic descent, a familiar chord progression—are not protectable on their own. But an author’s original selection and arrangement of such elements can be, though it receives only “thin” protection enforceable against virtually identical copying.