Grochocinski v. Mayer Brown Rowe & Maw, LLP, 2013 U.S. App. LEXIS 12728 (7th Cir. June 21, 2013):

Judicial estoppel is a flexible equitable doctrine designed to prevent "the perversion of the judicial process." In re Cassidy, 892 F.2d 637, 641 (7th Cir. 1990). The doctrine protects the courts from being "'manipulated by chameleonic litigants who seek to prevail, twice, on opposite theories.'" Ogden Martin Systems of Indianapolis, Inc. v. Whiting Corp., 179 F.3d 523, 527 (7th Cir. 1999) (quotations omitted); Ladd v. ITT Corp., 148 F.3d 753, 756 (7th Cir. 1998) ("the purpose of the doctrine . . . is to reduce fraud in the legal process by forcing a modicum of consistency on a repeating litigant"). It may be raised by any party, regardless of whether the party was prejudiced by the inconsistency, or by the court on its own motion. See In re Cassidy, 892 F.2d at 641. Because the doctrine is a "matter of equitable judgment and discretion," we review a district court's application of the doctrine for an abuse of that discretion. In re Knight-Celotex, LLC, 695 F.3d 714, 721 (7th Cir. 2012).

The application of judicial estoppel is "not reducible to any general formulation of principle," though the inquiry is typically informed by several factors. New Hampshire v. Maine, 532 U.S. 742, 750 (2001) (quotation omitted). The Supreme Court has identified three considerations to help guide the inquiry: (1) whether "a party's later position must be clearly inconsistent with its earlier position;" (2) whether "the party has succeeded in persuading a court to accept that party's earlier position, so that judicial acceptance of an inconsistent position in a later proceeding would create the perception that either the first or second court was misled;" and (3) whether "the party seeking to assert an inconsistent position would derive an unfair advantage or impose an unfair detriment on the opposing party if not estopped." Id. at 750-51 (quotations omitted). We have emphasized that these are not rigid requirements but "general guideposts that must be considered in the context of all the relevant equities in any given case." In re Knight-Celotex, LLC, 695 F.3d at 722.