When electing an official judge to preside over a court we want a candidate who is sufficiently educated in the law. When jurors are selected to decide the fate of an accused we would at least hope for the same. To properly judge "law," I believe a juror should be educated on all matters of the "law" and violations in question. Jurors have the authority to not only decide whether or not an accused is guilty of breaking a law and the absolute authority to decide the legitimacy of the law itself.
This is a major weapon in the arsenal of "We the People" in the fight against over reaching government. If we can decide for ourselves at the grass roots level that we will not hold our fellow citizens accountable for obscene policy, the leviathan that is government will be weakened. But, most judges will not allow this sort of information to be spoken in their court room. HB246 in New Hampshire will override the wishes of the bench if voted into law.
The question of ethics should be called into play against a judge that would not allow jury nullification to be mentioned as an option for a defendant in the first place. If someone's life and freedom are on the line for growing a non-government approved plant and harming no one then a jury should be aware of this information.