A case in which the Court will decide whether a defendant who pleaded guilty to possessing a firearm as a felon, in violation of 18 U.S.C. §§ 922(g)(1) and 924(a), is automatically entitled to plain-error relief if the district court did not advise him that one element of that offense is knowledge of his status as a felon, regardless of whether he can show that the district court’s error affected the outcome of the proceedings.