This is a Wa. State case for possession of pounds of cannabis.

WA[9][9] Controlled Substances -- Possession -- Unwitting Possession -- Burden of Proof -- In General Unwitting possession is an affirmative defense to a charge of unlawful possession of a controlled substance under RCW 69.50.401(d). The defendant has the burden of proving the defense. Placing on the defendant the burden of proving unwitting possession does not improperly shift the burden of proof; the burden of proving the elements of the charge remains with the State.


Your state may be different. Also if you live outside the U.S. it will be majorly different. If you give me both I can look and see if any case law is availble.

I just looked up virgina and no cases exist for unwitting possession, this generally means either no one has claimed it or it's a good defense which the state doesn't fight or appeal.