Skip to main content
Unpublished Paper
An Updated Quantitative Study of Iqbal's Impact on 12(b)(6) Motions
ExpressO (2011)
  • Patricia W Hatamyar, St. Thomas University School of Law
This is an empirical study of 1,333 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 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. For example, my earlier study found that Iqbal had a statistically significant upward effect on the relative risk of a court granting a 12(b)(6) motion with leave to amend, as compared to denying the motion. This updated study finds that Iqbal additionally has such an effect on a court’s granting a 12(b)(6) motion without leave to amend, as compare to denying the motion. Another new finding of this study is that a case is 1.74 times more likely to be entirely dismissed upon the granting of a 12(b)(6) motion under Iqbal than under Conley. My findings further confirm Iqbal’s adverse effect on civil rights plaintiffs. Under Conley, about 50% of the 12(b)(6) motions in constitutional civil rights cases were granted, with or without leave to amend. Under Iqbal, this percentage grew to 73%. Moreover, an analysis of only the constitutional civil rights cases in the database indicates that the relative risk of a 12(b)(6) motion being granted without leave to amend in such cases, compared to denied, is expected to be 3.30 times greater under Iqbal than under Conley, all other variables held constant.
  • empirical,
  • pleadings,
  • Iqbal
Publication Date
March 21, 2011
Citation Information
Patricia W Hatamyar. "An Updated Quantitative Study of Iqbal's Impact on 12(b)(6) Motions" ExpressO (2011)
Available at: