Antitrust Time Travel: Entry & Potential Competition
![handle is hein.journals/antil85 and id is 153 raw text is: ANTITRUST TIME TRAVEL:
ENTRY & POTENTIAL COMPETITION
SEAN P. SULLIVAN & HENRY C. SU*
How should claims of future entry, or its prevention, be addressed? To seri-
ously engage with these claims, one must be prepared to undertake what we
call analytical time travel: drawing connections between competition in the
past, present, and future through evidence, inference, and educated guess-
work. Modest attempts at time travel are familiar in antitrust. Some, like the
inference of a firm's competitive significance from its market share, assume
connections between past, present, and future competition.1 Others, like the
evaluation of challenges to mergers under Section 7 of the Clayton Act, as-
sume connections between present and future competition.2 But nowhere are
the demands of time travel more explicit, the tasks more challenging, or the
consequences more critical, than in the related doctrines of (1) the defense of
* Sullivan is a Professor of Law at the University of Iowa College of Law and a Senior Editor
of the Antitrust Law Journal. Su is a member of the California, District of Columbia, and Vir-
ginia Bars. This article reflects our views. It does not claim to represent the views of our employ-
ers, or of any institutions with which we are affiliated, or of any of our clients. We benefitted
from the comments of Erika Douglas, Eleanor Fox, Herb Hovenkamp, Christopher Leslie, Barak
Orbach, Douglas Rathbun, and student participants at the November 2022 Antitrust Scholars
Roundtable at the University of California, Irvine School of Law. We thank Kassandra DiPietro,
Cassandra Ehly, and Maya Sanaba for their research assistance. And we thank the Law Library at
the University of Iowa College of Law for help in collecting sources for this work. Correspon-
dence may be addressed to Sullivan at sean-sullivan@uiowa.edu.
' See, e.g., United States v. Gen. Dynamics Corp., 415 U.S. 486, 501 (1974) (Evidence of
the amount of annual sales is relevant as a prediction of future competitive strength, since in
most markets distribution systems and brand recognition are such significant factors that one
may reasonably suppose that a company which has attracted a given number of sales will retain
that competitive strength.).
2 E.g., Brown Shoe Co. v. United States, 370 U.S. 294, 332 (1962) ([T]he very wording of
§ 7 requires a prognosis of the probable future effect of the merger.) (emphasis omitted); United
States v. Phila. Nat'l Bank, 374 U.S. 321, 362 (1963) ([T]he ultimate question under § 7
[whether the effect of a merger would be substantially to lessen competition] . . . requires not
merely an appraisal of the immediate impact of the merger upon competition, but a prediction of
its impact upon competitive conditions in the future.).
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