Functionality Screens

86 Pages Posted: 27 Dec 2016 Last revised: 17 Apr 2020

Date Written: November 1, 2017


Among intellectual property (IP) doctrines, only utility patents should protect function. Utility patents offer strong rights that place constraints on competition, but they only arise when inventors can demonstrate substantial novelty after a costly examination. Copyrights, trademarks, and design patents are much easier to obtain than utility patents, and they often last much longer. Accordingly, to prevent claimants from obtaining “backdoor patents,” the other IP doctrines must screen out functionality. As yet, however, courts and scholars have paid little systematic attention to the ways in which these functionality screens operate across and within IP law.

We have four tasks in this Article. First, we identify three separate functionality screens that IP laws use: Filtering, Exclusion, and Threshold. Second, we illustrate the use of these different screens in copyright, trademark, and design patent laws. Each law takes a different approach to screening functionality. Third, we model the relative costs and benefits of the different screening regimes, paying particular attention to administrative and error costs and how these costs affect incentives and competition. Finally, we assess the current screening regimes and offers suggestions for how they might be improved. Among other things, our analysis provides a way to resolve the dispute currently before the U.S. Supreme Court in Star Athletica LLC v. Varsity Brands, Inc. over the copyrightability of cheerleader uniforms.

Suggested Citation

Buccafusco, Christopher J. and Lemley, Mark A., Functionality Screens (November 1, 2017). 103 Virginia Law Review 1293 (2017), Stanford Public Law Working Paper No. 2888094, Cardozo Legal Studies Research Paper No. 509, Available at SSRN: or

Christopher J. Buccafusco

Duke Law School ( email )

Box 90360
Durham, NC 27708-0360
United States

HOME PAGE: http://

Mark A. Lemley (Contact Author)

Stanford Law School ( email )

559 Nathan Abbott Way
Stanford, CA 94305-8610
United States

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