Heckler v. Community Health Services of Crawford County, Inc., 467 U.S. 51, 60, 104 S.Ct. 2218, 2224, 81 L.Ed.2d 42 (1984)). The government based its argument on the doctrines of sovereign immunity and separation of powers. Id. 15 . We also note that the separation of powers principles referred to in OPM v. Richmond are arguably implicated to a greater extent in the assertion of estoppel claims involving the application of military personnel regulations. Because plaintiff can establish neither the elements for a traditional estoppel claim nor affirmative misconduct, we do not address the broader issue of whether the military can ever be estopped from applying valid personnel regulations. 16 . See Schweiker v. Hansen, 450 U.S. 785, 790, 101 S.Ct. 1468, 1472, 67 L.Ed.2d 685 (1981) (<HOLDING>); INS v. Hibi, 414 U.S. 5, 8-9, 94 S.Ct. 19,
holding that erroneous oral advice did not constitute the type of affirmative misconduct that would be sufficient to estop the government from relying on a valid regulation requiring that certain social security benefit applications be in writing holding that plaintiff failed to plead facts sufficient to allege affirmative misconduct on the part of the government recognizing the benefit of alternative determinations in the social security review process holding that statements by an american consular officer that petitioners mother could not return to the united states because of her pregnant condition did not constitute affirmative misconduct sufficient to estop the government from relying on petitioners foreign birth to deny citizenship holding that an eic was neither a social security benefit nor a local public assistance benefit