What test should be used to determine prejudice from a constructive amendment under Rule 52(b)?

QUESTIONS PRESENTED The Grand Jury Clause of the Fifth Amendment demands “that a court cannot permit a defendant to be tried on charges that are not made in the indictment against him.” Stirone v. United States, 361 U.S. 212, 217 (1960). Because “[t]he right to have the grand jury make the charge on its own judgment is a substantial right,” this Court has long held that a violation of that right is prejudicial per se. Id. at 218-19. Nonetheless, lower courts have squarely divided over whether and, if so, how a defendant must show prejudice when a objection was not preserved at trial. Lower courts likewise have divided on what showing is required to prove that a constructive amendment error is “plain.” In the decision below, the Seventh Circuit doubled down on its outlier jurisprudence, which employs both the most demanding conception of prejudice and the most demanding conception of “plain” in the country. The questions presented are as follows: 1. What test, if any, should be used to determine whether a constructive amendment impacted a defendant’s substantial rights under Rule 52(b)? 2. What showing is required to determine whether a constructive amendment is “plain” error under Rule 52(b)?