532 U.S. 23 (2001)
Robert Sarkisian obtained two utility patents for a dual-spring design to keep outdoor signs upright despite adverse wind conditions.1 Respondent Marketing Displays, Inc., as holder of the now-expired patents, established a successful business manufacturing and selling sign stands that featured the visible dual-spring design near the base.2
After the patents expired, petitioner TrafFix Devices, Inc. began selling sign stands with a similar visible spring mechanism.3 TrafFix sent an MDI product abroad to have it reverse engineered and copied.4 TrafFix marketed its stands under the name WindBuster, similar to MDI's WindMaster name.5
MDI brought suit in the United States District Court for the Eastern District of Michigan alleging trademark infringement based on the similar names, trade dress infringement based on the copied dual-spring design, and unfair competition.6 TrafFix counterclaimed on antitrust theories.7 The district court ruled in favor of MDI on the trademark claim and found it not liable on the antitrust counterclaim.8
The district court granted summary judgment against MDI on the trade dress claim after finding no secondary meaning in the design and determining that the design was functional.9 The Court of Appeals for the Sixth Circuit reversed the trade dress ruling.10 The Supreme Court granted certiorari to resolve a split among the courts of appeals on the effect of an expired utility patent on trade dress protection claims.11
Whether the existence of an expired utility patent forecloses the possibility of the patentee claiming trade dress protection in the product's design?12
A utility patent is strong evidence that the features therein claimed are functional.13 When trade dress protection is sought for those features, strong evidence of functionality based on the previous patent exists.14 This evidence adds great weight to the statutory presumption that features are deemed functional until proved otherwise by the party seeking trade dress protection.15 Where the expired patent claimed the features in question, one who seeks to establish trade dress protection must carry the heavy burden of showing that the feature is not functional, for instance by showing that it is merely an ornamental, incidental, or arbitrary aspect of the device.16 A feature is also functional when it is essential to the use or purpose of the device or when it affects the cost or quality of the device.17
No. The central advance claimed in the expired Sarkisian utility patents is the dual-spring design, which is the essential feature of the trade dress MDI seeks to protect.18 MDI did not carry the heavy burden of showing that the feature is not functional.19 The patents demonstrate that the dual-spring design serves the important purpose of keeping the sign upright even in heavy wind conditions and prevents canting or twisting of the sign.20 The design affects the cost of the device as using three springs would unnecessarily increase the cost.21
The existence of an expired utility patent does not foreclose the possibility of claiming trade dress protection but provides strong evidence of functionality that MDI failed to overcome in this case.22