Master Leading Second Circuit copyright case establishing the two-step framework—copying and unlawful appropriation—judged in part by the ordinary lay listener and reserving key issues for the jury. with this comprehensive case brief.
Arnstein v. Porter is a cornerstone of American copyright infringement doctrine and a foundational case in the law of substantial similarity. Decided by the United States Court of Appeals for the Second Circuit, the opinion by Judge Jerome Frank articulated a now-classic two-step framework that separates the question whether the defendant copied from whether any copying rose to the level of unlawful appropriation. In doing so, the court drew a sharp line between expert analysis (permissible and often useful to prove copying) and the perspective of the ordinary lay listener (controlling on the ultimate question of unlawful appropriation).
The decision is equally significant for its procedural guidance. The court emphasized that credibility and lay reactions are quintessentially jury matters, making summary judgment or directed verdicts in many music plagiarism cases inappropriate where there is evidence from which a jury could infer access and similarity. As a result, Arnstein remains a staple in copyright courses for both its analytical framework and its insistence on the jury's role in evaluating artistic similarity.
Arnstein v. Porter, 154 F.2d 464 (2d Cir. 1946)
Plaintiff Ira B. Arnstein, a composer, alleged that defendant Cole Porter, a prolific and renowned songwriter, infringed several of Arnstein's copyrighted musical compositions. Arnstein claimed that Porter (directly or through intermediaries) obtained access to Arnstein's works—some of which Arnstein had circulated to publishers, agents, and persons in the popular music industry—and that Porter then incorporated original elements of Arnstein's music into widely distributed songs of Porter's. Porter denied any copying and contended that any similarities were either coincidental or concerned unprotectable musical elements common to the genre. The district court entered judgment for Porter before the case reached a jury, concluding that Arnstein had not presented sufficient evidence of access or actionable similarity. Arnstein appealed, arguing that circumstantial evidence of access and the similarities between the works created a triable issue of fact for a jury, particularly given that the ultimate inquiry turns on the reaction of the ordinary lay listener rather than technical musical dissection.
In a copyright infringement action alleging musical plagiarism, must the case be submitted to a jury where the plaintiff presents evidence from which a reasonable factfinder could infer (1) the defendant's copying of the plaintiff's work and (2) that any copying constituted unlawful appropriation judged by the response of the ordinary lay listener?
Copyright infringement requires proof of (1) copying of the plaintiff's work and (2) unlawful appropriation of protectable expression. Copying may be established by direct evidence or inferred from the defendant's access to the plaintiff's work plus similarities that are probative of copying. Unlawful appropriation (substantial similarity of protectable expression) is judged by the response of the ordinary lay listener, not by expert musical analysis. Expert testimony may assist on the copying inquiry but is generally improper on the unlawful appropriation inquiry. Issues of credibility and the lay listener's reaction are for the jury; where a reasonable jury could find access and unlawful appropriation from the evidence, judgment as a matter of law is inappropriate.
Yes. The Second Circuit reversed the judgment for the defendant and remanded for trial, holding that Arnstein's evidence—viewed favorably to him—was sufficient to require submission to a jury on both copying and unlawful appropriation under the ordinary lay listener standard.
The court first separated the infringement analysis into two distinct questions. On copying, the court explained that because direct evidence is rare, plaintiffs may rely on circumstantial proof, including access and similarities that are probative of copying. Arnstein adduced evidence from which a jury could infer that Porter or his associates had access to Arnstein's compositions through industry circulation and contacts; when coupled with asserted musical similarities, that proof sufficed to create a jury question on copying. The district court erred by discounting this evidence based on its own assessment of credibility and by requiring a level of direct proof inappropriate at the pretrial or peremptory-judgment stage. On unlawful appropriation, the court emphasized that the legal test is the reaction of the ordinary lay listener to the works as a whole—not technical musicological dissection. Although expert testimony can help show that similarities are probative of copying (e.g., by identifying patterns unlikely to occur by chance), experts should not decide, nor should a judge decide as a matter of law, whether the lay audience would regard the defendant as having appropriated the plaintiff's protected expression. That determination belongs to the jury. The court further noted that even if some similarities exist, there is no liability if the similarities concern only unprotectable elements (such as common or stock musical phrases) or if the copying is de minimis; however, whether the overlap crosses the line into unlawful appropriation is a quintessential fact question under the lay listener standard. Finally, the court stressed that credibility assessments—including judgments about the plaintiff's eccentricity or motives—are for the jury. Because Arnstein offered evidence from which a jury could find both access and substantial similarity of protectable expression, judgment for the defendant without a jury determination was improper, necessitating reversal and remand.
Arnstein v. Porter is a bedrock case in copyright law for three reasons: (1) it establishes the two-step framework distinguishing copying from unlawful appropriation; (2) it cements the ordinary lay listener (ordinary observer) standard for unlawful appropriation, reserving that evaluation to the jury; and (3) it limits summary judgment or directed verdicts in infringement cases where credibility and lay reaction are central. Modern courts continue to cite Arnstein when parsing the difference between probative similarity (to prove copying) and substantial similarity (to prove unlawful appropriation of protectable expression), and when determining the appropriate role of expert testimony.
Arnstein separates infringement into (1) copying—whether the defendant actually took from the plaintiff's work, which can be shown by direct evidence or inferred from access plus probative similarities; and (2) unlawful appropriation—whether the copying appropriated protectable expression to a substantial extent, judged by the reaction of the ordinary lay listener.
Experts may assist on the copying prong by identifying similarities that are probative of copying and by opining on issues like the likelihood of independent creation. However, on the unlawful appropriation prong, the test is the lay listener's response; expert musical dissection should not control the ultimate determination of substantial similarity of protectable expression.
Because credibility and the lay listener's reaction are central, Arnstein cautions that peremptory dispositions are often inappropriate where the plaintiff presents evidence from which a reasonable jury could find access and unlawful appropriation. If such evidence exists, the case should go to the jury.
No. Even if copying occurred, there is no liability unless the defendant appropriated protectable expression. Similarities confined to scènes à faire, common musical phrases, or other unprotectable elements are insufficient. The jury must decide whether the overlap concerns protected material and is substantial.
Independent creation is a complete defense. Even where access and similarities exist, the defendant may rebut an inference of copying by credible evidence of independent creation. Under Arnstein, such credibility disputes typically belong to the jury.
Arnstein v. Porter remains a touchstone for understanding how courts analyze alleged plagiarism in music and other expressive works. By bifurcating the inquiry into copying and unlawful appropriation, it clarifies evidentiary burdens and channels expert testimony to its proper role while reserving the ultimate similarity judgment to ordinary listeners.
Just as importantly, Arnstein underscores procedural humility: when evidence permits competing inferences about access, copying, and the lay audience's reaction, those issues are for a jury. Law students should remember Arnstein both for its doctrinal framework and for its enduring lesson about the allocation of decision-making between judge and jury in copyright cases.
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