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Mask Work Infringement

In analogizing semiconductor chips to traditional areas of copyright law, the legislative history notes that, just as a plagiarist who copies only one chapter of a book may be held liable for infringement, a person may be liable for copying a part of a mask work if it is a qualitatively important portion that results in substantial similarity.

This “substantial similarity” test has been applied in cases like Brooktree Corp. v. Advanced Micro Devices, Inc., 977 F.2d 1555 (Fed. Cir. 1992). In Brooktree, the court stated that “If the copied portion [of the mask work] is qualitatively important, the finder of fact may properly find substantial similarity under copyright law and the Semiconductor Chip Protection Act,” even if other portions of the chip were not copied. Id. at 1564.

The principle of “substantial similarity” recognizes that the existence of differences between the accused and copyrighted work may not negate infringement if the material portion of the copyrighted work is appropriated. 17 U.S.C.A. § 106. Whether the copied portions are “material portions” would require resolution on a fact-dependent, case-by-case basis. No hard and fast rule or percentage governs what constitutes “substantial similarity.” Substantial similarity may exist where an important part of the mask work is copied, even though the percentage of the entire chip which is copied may be relatively small. Brooktree Corp. v. Advanced Micro Devices, Inc., 977 F.2d 1555, 1564 (C.A. Fed. (Cal.),1992)


It is always recommended for a mask work applicant to identify the “novel points” in the design during the registration step (e.g., by specifying the material portions in the MW form when registering the mask work). The registration history may be introduced as one piece of evidence to show the materiality of the copied portions.

Mask Work Infringement Defense

As a defendant in a mask work infringement case, a statutory defense is “reverse engineering” authorized by the SCPA. This reverse engineering provision explicitly protects industry practices and encourages innovation.

Under the SCPA, it is not an infringement of an owner’s exclusive right and protected mask work for another person, through reverse-engineering, to photograph and to study the mask work for the purpose of analyzing its circuitry—correction—the circuitry, logic flow, and organization of the components used in the mask work and to incorporate such analysis into an original mask work.

To satisfy the “reverse engineering” defense, a defendant needs to establish at least two things: (1) the end product is a result of a reverse engineering effort (e.g., based on paper trials), and (2) the end product is itself original. In performing reverse engineering a person may disassemble, study, and analyze an existing chip in order to understand it. This knowledge may be used to create an original chip having a different design layout, but which performs the same or equivalent function as the existing chip, without penalty or prohibition.

Therefore, it is insufficient for a defendant to only demonstrate the reverse engineering effort without showing the “originality” of its accused design. In Brooktree, the Federal Circuit analyzed the defendant’s paper trail but held that “the sheer volume of paper” was not dispositive. Id. at 1569. The paper trail in that case was susceptible to an interpretation that the defendant copied the chip. The court held that the jury was entitled to weigh the evidence and consider the differences in the chips as well as the similarities, and could find the similarities sufficient to invalidate the reverse engineering defense. Id.


When using the “reverse engineering” defense authorized by SCPA, the defendant needs not only to demonstrate the evidence of the “reverse engineering”, but also that the accused product is original and a result of the reverse engineering process and effort.