Matter of Fernandez-Taveras, 25 I&N Dec. 834 (BIA 2012) (lawful permanent resident previously granted cancellation of removal following conviction for non-marijuana controlled substances offense is ineligible to adjust status as a defense to removal, because the controlled substances offense continues to exist for immigration purposes and cannot be waived by INA 212(h); INA 101(a)(13)(C), making excepting noncitizens granted cancellation of removal is inapplicable to those in proceedings under INA 237 because they are not returning from travel abroad).
http://www.justice.gov/eoir/vll/intdec/vol25/3757.pdf