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An Updated Quantitative Study of Iqbal's Impact on 12(B)(6) Motions

55 Pages Posted: 11 Jul 2011 Last revised: 27 Jul 2013

Patricia W. Hatamyar Moore

St. Thomas University School of Law

Date Written: March 21, 2011


This is an empirical study of 1,326 randomly-selected federal district court cases from a five-year period from 2005 to 2010. It is designed to measure the effect of the 2009 decision of Ashcroft v. Iqbal on federal district courts’ rulings on motions to dismiss complaints for failure to state a claim under Rule 12(b)(6). The present piece expands upon my earlier study, The Tao of Pleading: Do Twombly and Iqbal Matter Empirically? 59 AM. U. L. REV. 553 (2010).

Statistical analysis of the expanded database indicates a continuing, and in some ways strengthened, tendency of courts under Iqbal to grant 12(b)(6) motions, compared to courts under the previous standard set by Conley v. Gibson. The updated results indicate that the relative risk of a 12(b)(6) motion being granted without leave to amend, compared to denied, was expected to be 1.75 times more under Iqbal than under Conley, holding all other variables constant, and this increase is statistically significant. Further, the odds of the case being entirely dismissed upon the grant of a 12(b)(6) motion without leave to amend were 1.71 times greater under Iqbal than under Conley. Finally, the updated study continues to indicate that constitutional civil rights cases in particular were dismissed at a higher rate post-Iqbal than pre-Twombly.

In March 2011 the Federal Judicial Center released an extensive empirical study of the possible effect of Iqbal on 12(b)(6) motions. If read quickly and uncritically, the FJC’s overall conclusion, unlike mine, appears to be that Iqbal’s impact has been negligible, in particular when considering grants of 12(b)(6) motions without leave to amend.

Here, I also explore the FJC Study, and venture that it minimizes Iqbal’s impact in a variety of ways. Most critically, the FJC’s database omits pro se cases, which are disproportionately civil rights cases, and which my previous study found were more likely to be the subject of a successful 12(b)(6) motion under Iqbal than under Conley. In addition, the FJC’s database omits all cases in which the 12(b)(6) motion was granted on the basis of sovereign or qualified immunity; in other words, the FJC excluded the cases that were most like Iqbal itself. Finally, the FJC’s database (for studying the rulings on 12(b)(6) motions) is limited to a six-month period pre-Twombly (January to June 2006) and a six-month period post-Iqbal (January to June 2010), whereas my database contains cases running continuously for a five-year period from May 22, 2005 to May 18, 2010.

After attempting to limit my database to more closely parallel the FJC’s, my findings are broadly consistent with theirs: both the FJC and I found that 34% of 12(b)(6) motions were denied in 2006. In the first six months of 2010, the FJC found that the rate of denial of 12(b)(6) motions had fallen to 25%; I found that the rate of denial had fallen to 27%. Concomitantly, of course, that means that both studies found that the rate of granting 12(b)(6) motions, at least in part, increased significantly from 2006 to 2010. And both studies found that the increase in grants was primarily attributable to grants with leave to amend.

When I include all cases decided under Conley and Iqbal in my database, including those with pro se plaintiffs, my results show a much greater impact of Iqbal than do the FJC’s: 46% of the 12(b)(6) motions were granted in full under Conley, and 61% of the motions were granted in full under Iqbal.

As an aside, the comparison of my delimited results with the FJC’s tends to disprove the oft-stated hypothesis that orders granting 12(b)(6) motions are more likely to be “published” in computerized databases such as Westlaw than orders denying 12(b)(6) motions.

Keywords: civil procedure, pleading, Iqbal, civil rights, empirical legal studies, Federal Judicial Center

Suggested Citation

Moore, Patricia W. Hatamyar, An Updated Quantitative Study of Iqbal's Impact on 12(B)(6) Motions (March 21, 2011). University of Richmond Law Review, Vol. 46, p. 603, 2012. Available at SSRN:

Patricia W. Moore (Contact Author)

St. Thomas University School of Law ( email )

16401 N.W. 37th Ave.
Miami, FL 33054
United States
305-623-2342 (Phone)
305-623-2390 (Fax)

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