Perez-Mejia v. Holder, ___ F.3d ___, ___, 2011 WL 5865888 (9th Cir. Nov. 23, 2011), amending 641 F.3d 1143 (9th Cir. Apr. 21, 2011).

In Perez-Mejia v. Holder, the Ninth Circuit explained the elements of a successful claim of estoppel against the government:

It is well settled ... that the government may not be estopped on the same terms as a private litigant. Watkins, 875 F.2d at 706. A party seeking to raise estoppel against the government must establish affirmative misconduct going beyond mere negligence; even then, estoppel will only apply where the government's wrongful act will cause a serious injustice, and the public's interest will not suffer undue damage by imposition of the liability. Morgan v. Gonzales, 495 F.3d 1084, 1092 (9th Cir.2007) (quoting Watkins, 875 F.2d at 707). Moreover, a party cannot obtain estoppel against the government if he did not lose any rights to which he was entitled. Id.

There is no single test for detecting the presence of affirmative misconduct; each case must be decided on its own particular facts and circumstances. Affirmative misconduct does require an affirmative misrepresentation or affirmative concealment of a material fact by the government, although it does not require that the government intend to mislead a party. Watkins, 875 F.2d at 707 (citations omitted).

If a litigant survives this initial inquiry, the court considers four elements to determine if the government is estopped:

(1) the party to be estopped must know the facts; (2) he must intend that his conduct shall be acted on or must so act that the party asserting the estoppel has a right to believe it is so intended; (3) the latter must be ignorant of the true facts; and (4) he must rely on the former's conduct to his injury.

Morgan, 495 F.3d at 1092 (quoting Watkins, 875 F.2d at 709).

(Id. at ___.)