Why (Ever) Define Markets? An Answer to Professor Kaplow

21 Pages Posted: 14 Feb 2012

See all articles by Gregory J. Werden

Gregory J. Werden

U.S. Department of Justice - Antitrust Division

Date Written: February 13, 2012


Professor Louis Kaplow has argued that market delineation in antitrust should be abandoned because it is not useful in assessing market power or evaluating competitive effects. This article takes issue with that view, explaining that market delineation serves purposes overlooked by Professor Kaplow. Most importantly, market delineation separates active forces of competition from those in the background. This separation is significant in the application of economic models and in the narrative of presenting an antitrust case. This article also explains why Professor Kaplow’s proposed analyses dispensing with market delineation would break down in important circumstances.

Keywords: antitrust, relevant market, market delineation

JEL Classification: K21, L40

Suggested Citation

Werden, Gregory J., Why (Ever) Define Markets? An Answer to Professor Kaplow (February 13, 2012). Available at SSRN: https://ssrn.com/abstract=2004655 or http://dx.doi.org/10.2139/ssrn.2004655

Gregory J. Werden (Contact Author)

U.S. Department of Justice - Antitrust Division ( email )

450 Fifth Street, NW
9th Floor
Washington, DC 20530
United States
202-307-6366 (Phone)

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