Testing for Change in Procedural Standards, with Application to Bell Atlantic v. Twombly

64 Pages Posted: 12 Jul 2011 Last revised: 28 Aug 2015

Date Written: September 1, 2012


Measuring legal change - i.e., change in the way that judges decide cases - presents a vexing problem. In response to a change in the behavior of courts, plaintiffs and defendants will change their patterns of filing and settling cases. Priest and Klein's (1984) selection model predicts that no matter how favorable or unfavorable the legal standard is to plaintiffs, the rate at which plaintiffs prevail in litigation will not predictably change; thus, legal change cannot be measured with data on court outcomes. In this paper, I extend the selection model to develop a methodology for measuring legal change, even in the presence of selection effects. I apply this methodology to a recent, high profile Supreme Court case, Bell Atlantic Corp. v. Twombly. My model generates novel predictions, which are confirmed in the data, and I find that Twombly caused no legal change, even after accounting for possible selection effects.

Note: Previously circulated as "The Problem of Measuring Legal Change, with Application to Bell Atlantic v. Twombly".

Keywords: legal change, civil procedure, litigation, selection, Twombly

JEL Classification: K41

Suggested Citation

Hubbard, William H. J., Testing for Change in Procedural Standards, with Application to Bell Atlantic v. Twombly (September 1, 2012). 42 Journal of Legal Studies 35 (2013), U of Chicago Law & Economics, Olin Working Paper No. 575, Available at SSRN: https://ssrn.com/abstract=1883831 or http://dx.doi.org/10.2139/ssrn.1883831

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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