Economic Experts in Antitrust Litigation: Empirical Evidence from the Courts, 1890–2018

• Pages: 453-486
• Date: 01 January 2026
• Published date: 01 January 2026
• Author: Federico Ciliberto,Kenneth G. Elzinga,D. Daniel Sokol
• Subject Matter: Administrative & Public Law

ECONOMIC EXPERTS IN ANTITRUST LITIGATION:

EMPIRICAL EVIDENCE FROM THE COURTS, 1890–2018

F C

K G. E

D. D S*

INTRODUCTION ......................................... 454

I. SETTING THE STAGE ................................. 458

A. T A  E  A ......... 459

B. T P   J .................... 461

C. T P   E A ....... 463

D. T P  A S ........... 464

E. A S  P I ............................... 465

II. EMPIRICAL ANALYSIS OF ECONOMISTS IN ANTITRUST ... 465

A. D   D ....................... 466

B. A A L   C L:

T, P,  I ..................... 467

1. Time Trends.................................... 467

2. Number of Economists Involved and Academic/Private ... 469

3. Nature of Testimony.............................. 471

4. Amicus Briefs .................................. 472

5. Outcome Flipping ............................... 472

6. Statutes Involved ................................ 475

C. F   E: I 

A L D ......................... 478

CONCLUSION ........................................... 483

* Federico Ciliberto is Professor of Economics, Department of Economics, University of

Virginia. Kenneth G. Elzinga is the Robert C. Taylor Professor of Economics, Department of

Economics, University of Virginia. D. Daniel Sokol is the Carolyn Craig Franklin Chair in Law

and Professor of Law and Business, USC Gould School of Law and USC Marshall School of

Business, University of Southern California. We thank Lawrence J. White for his comments on

the database developed for this paper and Stefan Mitrovic and Tianwei Zhao for outstanding

research assistance. We gratefully acknowledge Sara Bensley at the University of Florida and

Reema Moussa for invaluable assistance in constructing our auxiliary dataset. We also thank

Roger Blair, Dennis Carlton, Javier Donna, George Hay, Roger Noll, Daniel Rubinfeld, David

Sappington, Richard Schmalansee, and Ted Snyder for comments on the paper.

453

INTRODUCTION

Edmund Burke endeared himself to economists with these words: “But the

age of chivalry is gone. That of sophisters, economists, and calculators, has

succeeded.”1 Years later, James DeLong gave a specific example of Burke’s

statement when he wrote “antitrust litigation not only needs economic analysis,

antitrust litigation is becoming economic analysis.”2 This was not always so.

Initially, antitrust litigation was accomplished sans input from economists.

But that time has passed and gone.

Today, antitrust lawyers litigate major antitrust cases with one or more

economists involved. The input of economists in antitrust litigation runs the

gamut from pretrial economic analysis to appearances as expert witnesses,

where economists interact with judges and juries. With few exceptions, econ-

omists play one of three roles in antitrust litigation: class certification (can an

economic case be made for combining plaintiffs into a class?), liability (did

something anticompetitive take place?), and damages (if there is an antitrust

violation, who gets compensated and how much?).

Many scholars have offered theoretical, descriptive, or qualitative analyses

about the role of economists in antitrust.3 We are not proposing to mediate

controversies about to what extent the shifts in how economists participate in

antitrust litigation are good or bad. Rather, we complement these works by

adding a quantitative aspect that shows a tension in the prevailing wisdom. On

the one hand, as the extant literature suggests, we find that over time the men-

tions of economic experts has increased in court decisions. On the other hand,

we also find that, in the most recent period in our study, the direct mention of

economic experts decreased rather than increased.4

1 E B, R   R  F 65 (Frank M. Turner ed.,

Yale U. Press 2003) (1790).

2 James V. DeLong, The Role, If Any, of Economic Analysis in Antitrust Litigation,

12 S. U.L. R. 298, 320 (1981).

3 See, e.g., Kenneth G. Elzinga, In the Beginning: The Creation of the Economic Expert in

Antitrust, 65 J.L. & E. S519 (2022); Jeffrey K. MacKie-Mason & Richard A. Pfau, Induce-

ments to Advocacy: The Economist as Independent Expert, in T R   A

E  L S 207, 213–14 (Daniel J. Slottje ed., 1999); Andrew I. Gavil,

After Daubert: Discerning the Increasingly Fine Line Between the Admissibility and Sufficiency

of Expert Testimony in Antitrust Litigation, 65 A L.J. 663 (1997); John E. Lopatka &

William H. Page, Economic Authority and the Limits of Expertise in Antitrust Cases, 90 C.

L. R. 617 (2005); Daniel L. Rubinfeld, Econometrics in the Courtroom, 85 C. L. R.

1048 (1985); Rebecca Haw, Adversarial Economics in Antitrust Litigation: Losing Academic

Consensus in the Battle of the Experts, 106 N. U. L. R. 1261 (2012).

4 We posit that this latter effect may be the result of institutionalization of economic analysis

in some cases that no longer requires direct mention of experts because judges have become

more comfortable evaluating the testimony of economists in antitrust cases.

454 A L J [Vol. 87

To investigate the engagement of experts in antitrust litigation, we have

constructed an original, hand-collected dataset of all federal antitrust cases

decided since the passage of the Sherman Act in 1890, in which an economist

was mentioned at the district court, circuit court of appeals, or Supreme Court

level in an opinion. The database contains information on 976 antitrust cases,

from the first such case, United States v. U.S. Steel Corp.5 in 1915 to all deci-

sions through December31, 2018.

We find, as shown in Figure 1, three breaks in the number of economists

mentioned in antitrust cases over the period of analysis, which suggest inflec-

tion points in antitrust that correspond with changes in the demand for analysis

by economists in the courts.6 The first break in the number of economists

mentioned is in 1974. Early that same year, the Supreme Court decided United

States v. General Dynamics Corp.7 In that case, the Court pushed back against

the structural presumption that high market shares and industry concentration

should block a merger. Rather, the Court recognized that other factors might

be a defense against a structural presumption. Because of General Dynamics,

the Supreme Court identified that market shares were not to be considered

the sole indicia of merger competitive effects.8 This meant that other factors

(including efficiencies) could make a difference.

The next break in the data occurs in 1994. With a lag, this break corresponds

with the introduction of the 1992 Horizontal Merger Guidelines.9 Unlike the

prior guidelines that focused on coordinated effects, the 1992 Guidelines

emphasized unilateral effects. Unilateral effects required more theoretical

5 223 F. 55 (D.N.J. 1915), aff ’d, 251 U.S. 417 (1920).

6 See Vivek Ghosal, The Genesis of Cartel Investigations: Some Insights from Examin-

ing the Dynamic Interrelationships Between U.S. Civil and Criminal Antitrust Investigations,

4 J. C L. & E. 61 (2008).

Economic Theory, in T P E  A 22–33 (Vivek Ghosal &

Johan Stennek eds., 2007); see also V ivek Ghosal & Joseph Gallo, The Cyclical Behavior of

the Department of Justice’s Antitrust Enforcement Activity, 19 I’ J. I. O. 27 (2001).

7 415 U.S. 486 (1974).

8 See id. at 498 (observing that, in Brown Shoe, “statistics concerning market share and

concentration, while of great significance, were not conclusive indicators of anticompetitive

effects”); see also Brown Shoe v. United States, 370 U.S. 294, 322 n.38 (1962) (“[O]nly a

further examination of the particular market—its structure, history and probable future—can

provide the appropriate setting for judging the probable anticompetitive effect of the merger”).

This limited the effect of United States v. Philadelphia National Bank, 374 U.S. 321, 365

n.42 (1963) (expressing a concern about “preventing even slight increases in concentration” if

“concentration is already great”).

9 U.S. D’  J & F. T C’, H M G

(1992).

2026] E E  A L 455