Is a defense argument that the witness protection program put issue in issue at trial?

The first factor, that the defense put the program in issue, is certainly present here. The second factor, that in light of the other evidence, the instruction did not "tilt" the jury toward guilt, is also satisfied here. This is true (1) because the other evidence of Matta's guilt was substantial, and (2) because of evidence that it was not Matta the witnesses feared, but other conspirators. Cf. United States v. Castleberry, 642 F.2d 1151, 1153 (9th Cir.) (extensive trial testimony about the witness protection program not reversible error, where there was evidence that others, and not the defendants, were responsible for witnesses' fear), cert. denied, 452 U.S. 966 (1981). Thus, the court's jury instruction was not reversible error.

H. The Aiding and Abetting Instruction

Matta also challenges the district court's jury instructions regarding the aiding and abetting charges. Matta did not object to these instructions below, and the parties agree that a plain error standard governs this our review. United States v. Castro, 887 F.2d 988, 992 (9th Cir.1989).