Trademark Functionality Revisited and Revised

70 Pages Posted: 6 May 2014

See all articles by Robert G. Bone

Robert G. Bone

University of Texas School of Law

Date Written: May 5, 2014


Functionality is one of the most important doctrines in modern trademark law, but it is also one of the most confused and unstable. The doctrine’s purpose, it is said, is to police the boundary between trademark, on the one hand, and patent and copyright, on the other, and to prevent trademark law from impeding product market competition. It accomplishes these goals by barring protection for source-identifying product features — so-called trade dress — when those features contribute to the functional performance of the product. For example, modern functionality law would bar protection for the distinctive shape of a wrench if that shape substantially improves the wrench’s leveraging ability, and it would do so even when the defendant’s use of the same shape is likely to cause consumer confusion. Not all trade dress is barred, however, and the challenge of functionality law is to determine which is and which is not — and why. Despite the doctrine’s lengthy history, its critical role in promoting intellectual property policies, and the considerable attention devoted to it in recent decades, courts and commentators still disagree about what functionality means, why functional marks should not be protected, and how far the functionality bar should extend.

This Article traces the history of the functionality doctrine, examines the various justifications offered to support it, and critically analyzes its policy foundations. It argues that the muddled state of functionality law today stems from lack of clarity and rigor at the normative level. Courts and commentators do not focus carefully enough on the policy justifications for the rules they adopt; they stress the benefits of a broad functionality bar without adequately considering its costs or appreciating the tricky practical problems involved in formulating administrable rules. In particular, many defenders of a broad functionality bar cite the doctrine’s role in enforcing a supposed “right to copy” any features not protected by patent or copyright. But they invoke this right to copy without explaining how or why the supposed right is capable of trumping trademark policies.

This Article takes a critical look at these policy arguments. It subjects the right to copy to a careful analysis and concludes that it is actually not a right at all, but rather a public domain policy that should be balanced against trademark policies to determine the scope of the functionality bar. Combining this public domain policy with the policies served by trademark protection, the Article outlines an analytical approach to designing optimal functionality rules and proposes reforms that alter existing functionality law in significant ways.

Keywords: trademark law, functionality doctrine, trademark history, TrafFix Devices, trademark policy, intellectual property, economics of trademark law

JEL Classification: K00, K11, K19, K29

Suggested Citation

Bone, Robert G., Trademark Functionality Revisited and Revised (May 5, 2014). U of Texas Law, Law and Econ Research Paper No. e554, Available at SSRN: or

Robert G. Bone (Contact Author)

University of Texas School of Law ( email )

727 East Dean Keeton Street
Austin, TX 78705
United States
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