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Substantial Similarity

Illustrates the "substantial similarity" doctrine from U.S. copyright law, using a set of case summaries.

Peter Pan Fabrics, Inc. v. Martin Weiner Corp., 274 F.2d 487 (2d Cir. 1960).


The defendant manufactured dresses using an ornamental design. The design largely resembled the plaintiffs’ “Byzantium” design. The defendant made some slight variation in details. Still, both designs had similar colors and motifs. According to the Second Circuit, “[b]oth designs have the same general color, and the arches, scrolls, rows of symbols, etc. on one resemble those on the other though they are not identical.” The district court granted a preliminary injunction against the defendant.

Court's Analysis

On appeal, the Second Circuit affirmed the preliminary injunction.

At the beginning of the court’s analysis, Judge Learned Hand acknowledged the difficulty of formulating a widely applicable rule for finding substantial similarity:

The test for infringement of a copyright is of necessity vague. In the case of verbal “works” it is well settled that although the “proprietor’s” monopoly extends beyond an exact reproduction of the words, there can be no copyright in the “ideas” disclosed but only in their “expression.” Obviously, no principle can be stated as to when an imitator has gone beyond copying the “idea,” and has borrowed its “expression.” Decisions must therefore inevitably be ad hoc. In the case of designs, which are addressed to the aesthetic sensibilities of an observer, the test is, if possible, even more intangible. No one disputes that the copyright extends beyond a photographic reproduction of the design, but one cannot say how far an imitator must depart from an undeviating reproduction to escape infringement.

The court found the “aesthetic appeal” of the two fabrics was the same. Even though the designs were not strictly identical, the court found that “the ordinary observer, unless he set out to detect the disparities, would be disposed to overlook them, and regard their aesthetic appeal as the same.” This formulation, sometimes called the “ordinary observer” test for substantial similarity, has been used in many subsequent cases.


Works at Issue