An aggravated felony conviction triggers immigration consequences so harsh and mandatory that in general most noncitizens suffering such a conviction must resign themselves to permanent banishment from the United States, no matter what the equities.[1]  Even a long-term permanent resident, who is convicted of an aggravated felony, will almost certainly be deported, never to return.  Noncitizens should strenuously avoid any conviction that could be considered an aggravated felony.

[1] Transactional Records Access Clearinghouse (TRAC) has published a detailed report at http://trac.syr.edu/immigration/reports/175/ (last visited 2/7/2007).

Other

AGGRAVATED FELONY"LEGISLATIVE ALERT"THIRD DRUG DRIVING PROPOSED AS AGGRAVATED FELONY
There is a bill now pending in Congress, S.1925, "To Reauthorize the Violence Against Women Act of 1994", which primarily deals with that topic, but also seeks to create authority for Indian tribal courts to prosecute non-Indians for domestic violence, and then sneaks in the following: "Section 1008. REMOVAL OF DRUNK DRIVERS (a) In General: Section 101(a)(43)(F) of the Immigration and Nationality Act (8 U.S.C. 1101(a)(43)(F) is amended by striking "for which the term of imprisonment" and inserting "including a third drunk driving conviction, regardless of the States in which the convictions occurred or whether the offenses are classified as misdemeanors or felonies under State or Federal law, for which the term of imprisonment is" and then another provision making that effective immediately on the date of the amendment. Thus anyone who got a third misdemeanor DWI, with one year imprisonment suspended, would have an aggravated felony, notwithstanding Leocal. This bill was reported out of the Senate Judiciary committee on February 7, 2012. Thanks to Tova Indritz.