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Is Pepsi Really a Substitute for Coke? Market Definition in Antitrust and IP

63 Pages Posted: 11 Apr 2012 Last revised: 2 Jan 2015

Mark A. A. Lemley

Stanford Law School

Mark P. P. McKenna

Notre Dame Law School

Date Written: April 10, 2012


Antitrust law explicitly depends on market definition. Many issues in IP law also depend on market definition, though that definition is rarely explicit.

Applying antitrust's traditional market definition to IP goods leads to some startling results. Despite the received wisdom that IP rights don't necessarily confer market power, a wide array of IP rights do exactly that under traditional antitrust principles. This result requires us to rethink both the overly-rigid way we define markets in antitrust law and the competitive consequences of granting IP protection. Both antitrust and IP must begin to think realistically about those consequences, rather than falling back on rigid formulas or recitation of the mantra that there is no conflict between IP and antitrust.

Suggested Citation

Lemley, Mark A. mname and McKenna, Mark P. mname, Is Pepsi Really a Substitute for Coke? Market Definition in Antitrust and IP (April 10, 2012). Georgetown Law Journal, Vol. 100, p. 2055, 2012; Stanford Law and Economics Olin Working Paper No. 424; Notre Dame Legal Studies Paper No. 12-75. Available at SSRN: or

Mark A. Lemley (Contact Author)

Stanford Law School ( email )

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

Mark P. McKenna

Notre Dame Law School ( email )

P.O. Box 780
Notre Dame, IN 46556-0780
United States
(574) 631-9258 (Phone)

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