Appellant Wright was convicted of transporting marijuana after the trial court declined to instruct the jury that the Compassionate Use Act of 1996 (CUA) provided a defense to that charge. The appellate court found that the refusal was prejudicial error and reversed. The California Supreme Court granted review to resolve the issue of whether and under what circumstances an implied defense to transportation existed under the CUA. While the case was pending, the Legislature enacted the Medical Marijuana Program (MMP) which addressed issues not included in the CUA. Among its provisions, the MMP specifically provided an affirmative defense to the crime of transportation of marijuana by individuals protected by the CUA. The MMP has been held to apply retroactively. Here, appellant contends that the MMP applies to this case and provides an alternative ground to affirm the judgment of the appellate court. The California Supreme Court agreed that the MMP applies retroactively to cases pending at the time of its enactment, and therefore to this case. Further, because appellant presented sufficient evidence to entitle him to a CUA instruction as a defense to transportation, it was error for the trial court to have refused the instruction. However, unlike the Court of Appeal, the Supreme Court found the error harmless.