7.9 SPECIFIC ISSUE UNANIMITY
Ordinarily, the "general unanimity instruction suffices to instruct the jury that they must be unanimous on whatever specifications form the basis of the guilty verdict." United States v. Lyons,472 F.3d 1055, 1068 (9th Cir.2007) (quoting United States v. Kim, 196 F.3d 1079, 1082 (9th Cir.1999)).
Nonetheless, a specific unanimity instruction is required if it appears that there is a "genuine possibility of jury confusion or that a conviction may occur as the result of different jurors concluding that the defendant committed different acts." Id. (citing United States v. Anguiano, 873 F.2d 1314, 1319 (9th Cir.1989)) (internal quotation marks omitted); compare United States v. Echeverry, 719 F.2d 974, 975 (9th Cir.1983) (finding that unanimity instruction regarding specific conspiracy should have been given in light of proof of multiple conspiracies) with Kim, 196 F.3d 1079 (no abuse of discretion to refuse to give specific unanimity instruction when the defendant was charged with a single crime based on a single set of facts and where prohibited acts were merely alternative means by which the defendant may be held criminally liable for the underlying substantive offense). Thus, the Committee recommends the court consider the need for a specific unanimity instruction to avoid juror confusion if (1) the evidence is factually complex, (2) the indictment is broad or ambiguous, or (3) the jury’s questions indicate that it may be confused. See Anguiano, 873 F.2d at 1319-21.
A specific unanimity instruction may also be necessary to avoid constitutional error. For example, when self-defense is at issue, a jury must unanimously reject the defense in order to convict. United States v. Ramirez, 537 F.3d 1075, 1083 (9th Cir.2008) (approving instruction that included specific unanimity within the self-defense instruction consistent with this instruction and Instruction 6.8 (Self-Defense)); see also Richardson v. United States, 526 U.S.813 (1999) (continuing-criminal-enterprise prosecution requires unanimity as to the specific violations that make up a "continuing series of violations"); but see United States v. Nobari, 574 F.3d 1065, 1081 (9th Cir.2009) (although unanimity is required to reject an affirmative defense, a specific unanimity instruction is not required for most affirmative defenses).
A specific unanimity instruction is not required, however, to distinguish an aiding-and-abetting theory of liability from the underlying substantive crime. United States v. Garcia, 400 F.3d 816, 820 (9th Cir.2005). Nor is one required as to a particular false promise in a mail fraud case or as to a particular theory of liability underlying a "scheme to defraud" so long as jurors are unanimous that the defendant committed the underlying substantive offense. Lyons, 472 F. 3d at 1068-69. Likewise, jurors do not need to agree unanimously as to which particular act or actions constituted a substantial step toward the commission of a crime in a prosecution for an attempt to commit a crime. United States v. Hofus, 598 F.3d 1171, 1176 (9th Cir.2010). Further, when a defendant is charged with "a single continuous act of possession," jurors need not reach unanimous agreement on the pieces of evidence they find persuasive in establishing that possession. United States v. Ruiz, 710 F.3d 1077, 1081-82 (9th Cir. 2013); see also United States v. Mancuso, 718 F.3d 780, 791 (9th Cir.2013).
When a specific unanimity instruction is necessary, the Committee recommends including in the substantive instruction the phrase " . . .with all of you agreeing [as to the particular matter requiring unanimity]." See United States v. Garcia-Rivera, 353 F. 3d 788, 792 (9th Cir.2003) (unanimity instruction "fatally ambiguous" when jury could have understood they were required to decide unanimously only that possession occurred during any of three times enumerated).