Momin v. Gonzales, 447 F.3d 447 (5th Cir. Apr. 25, 2005) (8 C.F.R. section 245.1(c)(8), which deems arriving aliens who are in removal proceedings ineligible to apply for adjustment of status to lawful permanent resident, is not ultra vires to INA 245).
http://caselaw.lp.findlaw.com/data2/circs/5th/0560119cv0p.pdf