What is the standard of review of a district court's denial of a defendant's proposed jury instruction?

1 As noted by the government, there is some dispute within this circuit regarding the appropriate standard of review of a district court's denial of a defendant's proposed jury instruction. See, e.g., United States v. Dinkane, 17 F.3d 1192, 1200 (9th Cir.1994) (noting conflict). We adopt the resolution proposed in United States v. Gomez-Osorio, 957 F.2d 636, 642 (9th Cir.1992): "If the parties dispute whether the required factual foundation exists [for a theory of defense], the court should apply an abuse of discretion standard of review. [I]f the ultimate issue is whether other instructions, in their entirety, adequately cover the defense theory ... [such a question] is a question of law and ... should be reviewed de novo." As this is a question of factual foundation, we review for an abuse of discretion.