What is the test for a motion to reverse a conviction of conspiracy to obstruct the course of justice?

in the same criminal conspiracy . . . ." United States v. Spinelli, 352 F.3d 48, 55 (2d Cir. 2003) (citations omitted). "The decision to sever a joint trial of federal defendants is committed to the sound discretion of the trial judge[, and is c]onsidered virtually unreviewable." United States v. Diaz, 176 F.3d 52, 102 (2d Cir. 1999) (internal quotation marks and citations omitted). "[T]o compel reversal, the defendant has the heavy burden to show prejudice so severe that his conviction constituted a miscarriage of justice." United States v. Ferguson, 676 F.3d 260, 286-87 (2d Cir. 2011) (internal quotation marks omitted).