I. Whether the district court lacked subject matter jurisdiction over Mr. Walker's case because the indictment failed to state an offense against the laws of the United States.

II. Whether, when applying plain-error review based on an intervening United States Supreme Court decision, a circuit court of appeals may review matters outside the trial record to determine whether the error affected a defendant's substantial rights or impacted the fairness, integrity, or public reputation of the trial.

Whether the district court lacked subject matter jurisdiction