The Effects of Twombly and Iqbal

78 Pages Posted: 12 Aug 2016 Last revised: 20 Apr 2017

Multiple version iconThere are 2 versions of this paper

Date Written: April 19, 2017


Ever since Twombly and Iqbal introduced the doctrine of plausibility pleading, a cottage industry of legal scholars (including myself) has undertaken to detect the effects of Twombly and Iqbal on litigants and case outcomes. Results so far have been equivocal, and it has been hard to make sense of the disparate methodologies and findings. In this paper, I develop a comprehensive yet non-technical framework for empirically testing the effect of Twombly and Iqbal on lower courts and litigants, taking into account a wide range of confounding factors and the numerous ways in which Twombly and Iqbal may have indirectly affected litigant behavior. Using this framework, I test for effects of Twombly and Iqbal on district court and litigant behavior using two datasets—one of administrative data covering over 700,000 cases, and one of detailed, hand- and machine-coded docket and complaint data covering a representative sample of nearly 2,000 cases. I also review existing findings. I find only limited evidence that Twombly and Iqbal, the two most important pleading cases in 50 years, have had a major effect on the behavior of lawyers and judges across all cases. For represented plaintiffs, rates of dismissal with prejudice have held steady, motions to dismiss remain uncommon, and settlement and filing patterns have not changed appreciably in the wake of Twombly and Iqbal. There is, however, some evidence of effects—potentially major effects—on pro se plaintiffs. Further, while case outcomes for represented plaintiffs have been largely unaffected by Twombly and Iqbal, there is evidence that lawyers changed their pleading and motion practice in the wake of those cases.

Keywords: civil procedure, courts, litigation, pleading, dismissal

JEL Classification: K41

Suggested Citation

Hubbard, William H. J., The Effects of Twombly and Iqbal (April 19, 2017). University of Chicago Coase-Sandor Institute for Law & Economics Research Paper No. 773; U of Chicago, Public Law Working Paper No. 591. Available at SSRN: or

William H. J. Hubbard (Contact Author)

University of Chicago Law School ( email )

1111 E. 60th St.
Chicago, IL 60637
United States
773-834-8999 (Phone)

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