Is there any case law where a jury has been instructed to find that a mere presence was a factor in the finding of aiding and abetting?

The government need not prove that Koach and Colburn intended to violate each element of the principal's offense; it need only show that they knowingly provided substantial assistance to another's violation. United States v. Kessi, 868 F.2d 1097, 1103 (9th Cir.1989). The aiding and abetting instruction was therefore correct. It is not clear why a "mere presence" instruction is germane in the circumstances of this case; in any event, the district court instructed that the jury had to find that Koach and Colburn acted willfully, knowingly, and intentionally, and that an "honest belief or good faith belief" that statements and representations were true was a complete defense. In light of the instructions that were given, there can be no error in failing to discuss "mere presence."