AmEX book

Antitrust Analysis of Platform Markets:
Why the Supreme Court Got It Right in American Express

David S. Evans
Richard Schmalensee


Platform businesses that facilitate connections between different stakeholders play an increasingly prominent role in the economy. Several of the largest firms in the world operate platforms. In 2018, the U.S. Supreme Court issued a seminal decision, Ohio et. al. v. American Express, on the analysis of antitrust issues involving these sorts of businesses. In Antitrust Analysis of Platform Markets: Why the Supreme Court Got It Right in American Express, David S. Evans and Richard Schmalensee explain the economic basis for the Court’s analysis. The Court found that antitrust analysis of two-sided platforms that enable transactions between distinct groups, such as cardholders and merchants, must account for both groups in market definition and the analysis of anticompetitive effects The authors describe the problems with alternative approaches that were presented to the Court and consider the key criticisms levied against the Court’s analysis. The book is based on a series of articles the authors wrote leading up to and following the decision including the amicus brief they submitted to the Court. Given the growing importance platforms in the economy, antitrust will deal with more cases governed by the American Express decision in the U.S., as well as judgments of other courts on similar issues around the world. Many questions about the sound antitrust analysis of platform businesses remain unanswered. This book makes a timely contribution to the ongoing debate about how to apply antitrust to platforms and the digital economy in which they play a significant role.

The book constitutes a useful tool to not only interpret, but to potentially predict, the current and forthcoming application and direction of competition law in media markets in the United States, the European Union, and other jurisdictions worldwide.

Table of Contents

Authors’ Note


Where's The Harm?   

The Rule of Reason    

Under and Over Enforcement  

Two-Sided Red Herrings   

All That Jazz  

Supreme Court Decision   

Brief for the United States as Respondent Supporting Petitioners  

Brief of 28 Professors of Antitrust Law as Amici Curiae Supporting Petitioners  

Brief for Amici Curiae John M. Connor, Martin Gaynor, Daniel McFadden, Roger Noll, Jefferey M. Perloff, Joseph A. Stiglitz, Lawrence J. White, and Ralph A. Winter in Support of Petitioners

Authors’ Bios

CPI’s Bookshelf

THE EVOLUTION OF ANTITRUST IN THE DIGITAL ERA: Essays on Competition Policy Volume 2
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CONTROLLING MERGERS AND MARKET POWER: A Program for Reviving Antitrust in America - JOHN KWOKA
Media Markets and Competition Law book cover small
Internet Competiton Regulation Online Platforms
Competition Policy Asia

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This is a very timely publication by two well-known authors who are masters of their craft. Their clear analysis of the complex antitrust issues raised by multisided platforms, and in particular their discussion of the U.S. Supreme Court decision in American Express, will be of great value to practitioners and judges alike.”

Sir Christopher Bellamy QC

Chairman of the Global Competition Practice, Linklaters

For over 125 years, the antitrust laws have had to adapt to incremental and disruptive changes in the economy. Today, many businesses operate multi-sided platforms supported by technologies that literally did not exist a generation ago. The antitrust laws must provide a framework for assessing competition and potentially anti-competitive conduct in this new and evolving context. This body of work by David Evans and Richard Schmalensee provides an enormously valuable primer for practitioners, market participants, and courts on how to think about, analyze and, ultimately, judge the behavior of participants in a world populated by such multi-sided platforms.”

Evan R. Chesler

Partner, Cravath

David Evans and Richard Schmalensee have made a short but powerful contribution to the complex legal and economic issues that surround the operation of platform markets.  Their strong defense of the Supreme Court’s recent decision in Ohio v. American Express offers a powerful explanation of how these platform markets require sensitive treatment lest a powerful force for social innovation in payment markets be hobbled by an overzealous enforcement of the antitrust laws.”

Richard Epstein

Professor of Law, New York University

David Evans and Dick Schmalensee have been teaching us about two-sided markets for over 20 years. Their work on the subject significantly informed the Supreme Court’s 2018 decision in Ohio v. American Express – where the Court not only adopted their analysis, but also cited Evans 31 times (!) and Schmalensee 17. So it is not a huge leap to conclude that, when these guys tell us about the American Express decision, they know what they are writing about. As other industries, such as Internet platforms, come under increasing competitions focus, the Evans/Schmalensee analysis will provide an invaluable guide.”

Jonathan M. Jacobson

Partner, Wilson Sonsini

For a clear, concise, and complete exposition of platform markets – one of the hottest topics in antitrust law – you will find no better source than Evans & Schmalensee. These two leading economists, whose scholarship and friend-of-the-court brief helped shape the Supreme Court’s Amex decision, explain the economics of multi-sided platforms and anticipate applying two-sided market analysis in various contexts, including online digital markets, in this indispensable book.”

Elai Katz

Partner, Cahill Gordon & Reindel

Recognition of the unique character of multisided platforms is perhaps the most significant antitrust innovation of the last half century. Based on insights by the legendary William F. Baxter, accurate understanding of such platforms has attained critical importance given the unprecedented growth and increasing impact of digital platform businesses. The authors – both preeminent figures in industrial organization, econometrics, and related fields – led in the steady refinement and dissemination of sound platform analysis, ultimately persuading the Supreme Court to adopt their key insights. This volume lucidly summarizes and explains their ideas and traces their ultimate acceptance as authoritative U.S. antitrust precedent.”

Tad Lipsky

Director, GAI Competition Advocacy Program, George Mason University

Evans & Schmalensee provide an in-depth look at the foundations and implications of an important Supreme Court antitrust precedent. It is vital reading for anyone interested in how current antitrust law assesses the competitive implications of platforms, one of the hottest legal topics today.”

Maureen K. Ohlhausen

Partner, Baker Botts

David Evans and Richard Schmalensee have shown the economics profession the importance of multisided platforms. In this book they bring their command of the subject to bear on the AmEx case, in which the Supreme Court’s seminal decision copiously cited their analysis of platforms. Now Evans & Schmalensee persuasively frame their advice…that proper analysis should look at the whole picture – all sides – to evaluate these platforms, and better understand the factors that undergird the likelihood of platform success and failure.”

David J. Teece

Professor, Haas School of Business, University of California, Berkeley

As primary contributors to our economic understanding of multisided markets, no two scholars are better situated to analyze the Supreme Court's decision in Ohio v. American Express and its implications for antitrust policy.  Evans & Schmalansee deliver characteristically deep insight and careful analysis in explaining the economic and legal implications of the Supreme Court's decision.  As digital markets become a more prominent feature of the regulatory landscape, ‘Antitrust Analysis of Platform Markets: Why the Supreme Court Got It Right in American Express,’ is essential reading for antitrust practitioners, economists, regulators, and policymakers.”

Joshua D. Wright

University Professor of Law, George Mason University

David Evans and Richard Schmalensee’s new book provides an insightful and accessible analysis of one of the most pressing issues of our time: How antitrust law will apply to the platform economy. This nuanced discussion of the U.S. Supreme Court’s recent American Express decision by two of the world’s leading experts on the economics of two-sided markets is a must-read for anyone interested in the future of the digital economy.”

Christopher S. Yoo

Professor of Law, University of Pennsylvania
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