The 2023 Merger Guidelines: Law, Fact, and Method.

The final version of the 2023 Merger Guidelines, which were issued in December 2023, is a vast improvement over an earlier draft—which indicates that the Agencies took the many comments that they received on a draft very seriously. These Guidelines break some new ground that older Guidelines did not address, and make many positive contributions, which this paper spells out. They are also excessively nostalgic for a past era, however, and this may explain their propen sity to treat empirical questions as issues of law: This is one way to insulate these Guidelines from further revision. The excessive reliance on one decision, Brown Shoe, is unfortunate—particularly since that decision has been so often repudiated, even by the Supreme Court itself. This paper pays particular attention to: the Guidelines' treatment of structural triggers and direct measures of competitive effects; their aggressive position on potential competition mergers; their willingness to weigh a "trend" toward concentration as a factor; and their treatment of serial acquisitions. The Guidelines include a welcome new section on mergers involving multi-sided networks, although their view of networks is too one-sided; and the Guidelines also contain an expanded section on mergers with harmful effects on suppliers—including labor. The Guidelines' treatment of market definition is likely to lead to underenforcement because they define markets too broadly. Finally, the Guidelines could have made better use of recent retrospective studies—many of which would have provided further support for the substantive positions that the Guidelines take. [ABSTRACT FROM AUTHOR]