Trademarks

The Spring That Could Not Be Owned: TrafFix Devices v. Marketing Displays and the Functionality Bar

The Supreme Court held that a feature claimed in an expired utility patent is presumptively functional and barred from trade dress protection, and that the availability of alternative designs does not rescue a functional feature.

May 19, 2025
An orange temporary road sign standing upright on a spring-loaded base beside a highway
Marketing Displays claimed the visible dual-spring base of its road signs as trade dress; the Court asked whether a once-patented mechanism could be owned forever. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

When a utility patent expires, the invention it protected is supposed to fall into the public domain, free for anyone to copy. Trade dress law promises something different and potentially endless: protection, renewable indefinitely, for features that identify a product’s source. The collision between those two regimes is the subject of TrafFix Devices, Inc. v. Marketing Displays, Inc., 532 U.S. 23 (2001) (No. 99-1571, argued November 29, 2000, decided March 20, 2001). A unanimous Supreme Court, in an opinion by Justice Kennedy, reversed the U.S. Court of Appeals for the Sixth Circuit and held that the feature at the center of the case—a dual-spring mechanism that keeps road signs upright in the wind—was functional and therefore could never be trade dress, no matter how recognizable it had become. The decision is the modern cornerstone of the functionality doctrine and a sharp warning to anyone who hopes to convert an expired patent into a perpetual trademark.

At a glance

  • Case: TrafFix Devices, Inc. v. Marketing Displays, Inc., 532 U.S. 23 (2001); No. 99-1571 (argued Nov. 29, 2000; decided Mar. 20, 2001).
  • Court: U.S. Supreme Court; Justice Kennedy writing for a unanimous Court.
  • Posture: Trade dress infringement action under § 43(a) of the Lanham Act after the relevant utility patents expired; the Sixth Circuit had held the trade dress claim could proceed, and the Supreme Court granted certiorari.
  • Holding: The dual-spring design is a functional feature for which there is no trade dress protection; an expired utility patent is strong evidence that the features it claimed are functional, and the availability of alternative designs does not defeat functionality.
  • Status: Sixth Circuit reversed.

The dual-spring design and its expired patents

Marketing Displays, Inc. (MDI) had developed a mechanism using two closely spaced coil springs to keep temporary outdoor signs—the kind used at road construction sites—standing upright in heavy wind. MDI held utility patents on that dual-spring design. When the patents expired, a competitor, TrafFix Devices, reverse-engineered MDI’s sign stands and began selling its own version with a visibly identical dual-spring base. MDI sued, claiming that the dual-spring look had become recognizable to buyers and therefore functioned as protectable trade dress identifying MDI as the source.

The district court rejected the trade dress claim, finding the design functional. The Sixth Circuit reversed, reasoning in part that MDI might prevail because competitors could achieve the same wind-resistance with alternative configurations—so the particular dual-spring arrangement was not, in the appeals court’s view, competitively necessary. The Supreme Court took the case and reversed, in the process recalibrating how courts decide whether a feature is functional.

Functionality, restated

Justice Kennedy began with the settled definition the Court had drawn from Inwood Laboratories, Inc. v. Ives Laboratories, Inc. and reaffirmed in Qualitex Co. v. Jacobson Products Co., 514 U.S. 159 (1995): a product feature is functional, and cannot serve as a trademark, “if it is essential to the use or purpose of the article or if it affects the cost or quality of the article.” Measured against that standard, the dual-spring design was plainly functional. The springs were not decorative flourishes; they were the very thing that made the sign stand work. A device whose entire reason for existence is to keep a sign upright in the wind is “essential to the use or purpose of the article” by definition.

The doctrinal stakes are the relationship between patent and trademark. A utility patent grants a limited monopoly over a useful invention precisely so that, when the term ends, the public may freely use it. To allow trade dress to lock up the same functional feature indefinitely would let trademark law undo the bargain at the heart of the patent system. Functionality is the doctrine that prevents that result.

The expired patent as “strong evidence”

The opinion’s most quoted contribution is its treatment of the parties’ patent history. Because MDI had held utility patents claiming the dual-spring mechanism, the Court held that those expired patents carried “vital significance” in the trade dress analysis. A utility patent, Justice Kennedy wrote, is “strong evidence that the features therein claimed are functional.” The patentee who has touted a feature’s utility to obtain a patent will find it difficult to deny that same utility when later claiming the feature as a source identifier.

Crucially, the Court placed the burden squarely on the trade dress claimant. Where the feature was the central advance of an expired utility patent, the party seeking 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.” MDI could not meet that burden; its own patents had described the dual-spring design as the mechanism that solved the wind-resistance problem.

Why alternative designs do not save a functional feature

The Court’s sharpest correction was directed at the Sixth Circuit’s reliance on the availability of alternative designs. The lower court had reasoned that because competitors could keep signs upright using other configurations—three springs, a different spacing—the dual-spring design was not competitively necessary and therefore arguably non-functional. The Supreme Court rejected that move for traditional, utilitarian functionality. “There is no need,” Justice Kennedy wrote, “to consider the availability of alternative designs, because the feature cannot serve as a trademark” once it is shown to be essential to the article’s use or to affect its cost or quality. Put differently: when a feature is functional under the Inwood test, the existence of substitutes is beside the point.

The Court took care to situate the “competitive necessity” inquiry where it belongs. The question whether exclusive use of a feature would put competitors at a significant non-reputation-related disadvantage—the test associated with Qualitex—is the proper tool for aesthetic functionality, not for features that are functional in the conventional, utilitarian sense. By disentangling the two, TrafFix clarified that traditional functionality is established by the Inwood formula alone, and that alternative-designs evidence enters only in the distinct, aesthetic context. This division of labor is one of the case’s most durable doctrinal legacies, and lower courts have wrestled ever since with exactly where the line falls.

Open questions

  • How heavy is the “heavy burden”? TrafFix shifts a demanding burden onto the trade dress claimant whose feature appeared in an expired utility patent, but it does not specify what evidence—beyond “ornamental, incidental, or arbitrary”—suffices to rebut the presumption of functionality.
  • What counts as the “central advance” of a patent? The strong-evidence rule applies to features that were the heart of the patent. Disputes recur over whether a particular claimed element was central or merely peripheral to the invention.
  • Where does aesthetic functionality survive after TrafFix? By confining the competitive-necessity test to the aesthetic context, the Court left lower courts to police a boundary that remains unstable, especially for design features that are both useful and attractive.

Implications

  • An expired utility patent is a liability for trade dress. The very document that once protected a feature now supplies strong evidence that the feature is functional and unprotectable.
  • Alternative designs will not rescue a utilitarian feature. For traditional functionality, the existence of substitute configurations is irrelevant; the Inwood test controls.
  • Claim drafting has downstream consequences. Touting a feature’s advantages in a patent specification can foreclose a later trade dress claim over the same feature.
  • Separate your functionality theories. Litigants must decide at the outset whether they are arguing utilitarian functionality (Inwood) or aesthetic functionality (Qualitex); conflating the two invites reversal.
  • Trade dress is for the look that does not make the product work. Features that are ornamental, incidental, or arbitrary remain protectable; features essential to use or that affect cost or quality do not.

Frequently asked questions

What is the functionality doctrine, in plain terms? It is the rule that a product feature cannot be a trademark if the feature is essential to the product’s use or purpose, or if it affects the product’s cost or quality. The doctrine keeps trademark law from granting perpetual control over useful features that patent law reserves for limited terms.

Why did Marketing Displays lose even though buyers recognized its dual-spring base? Recognition is irrelevant once a feature is functional. The dual-spring design was essential to keeping the signs upright, so it could not be trade dress no matter how distinctive it had become in the marketplace.

Does it matter that competitors could use a different spring arrangement? No—not for traditional functionality. The Court held that the availability of alternative designs does not undercut the functionality of a feature that is essential to the article’s use. Alternative-designs evidence belongs to the separate inquiry into aesthetic functionality.

Authorities and sources