Does lack of authorization constitute an essential element of the crime of possession of a controlled substance?

Even were we to conclude that the defect in the indictment was not fatal and that the trial court's evidentiary ruling, which resulted in a misallocation of the burden of proof, was not reversible error because of the evidence in the record tending to suggest the nonapplicability of the medical exception, ⁸ reversal would still be necessary because of the jury instructions. The instructions failed to indicate that lack of authorization is an element of the crime or that the jury must find lack of authorization under the medical exception beyond a reasonable doubt before it could convict Deal. This court, both in Black, supra, 512 F.2d at 868, and in United States v. Davis, 564 F.2d 840, 845 (9th Cir. 1977), has defined lack of authorization to distribute or dispense controlled substances as an essential element of the offense.