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Monopoly Power And Market Power In Antitrust Law, Thomas G. Krattenmaker, Robert H. Lande, Steven C. Salop

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This article seeks an answer to a question that should be well settled: for purposes of antitrust analysis, what is 'market power' and/or 'monopoly power'? The question should be well settled because antitrust law requires proof of actual or likely market power or monopoly power to establish most types of antitrust violations.

Examination of key antitrust law opinions, however, shows that courts define 'market power' and 'monopoly power' in ways that are both vague and inconsistent. We conclude that the present level of confusion is unnecessary and results from two different but related errors:

(1) the belief or suspicion that …