If you think this sounds like anarchy, you have been infected with notions alien to jury trial. Think what it would mean to sit on a jury, and expose someone to financial loss, imprisonment or death for breaking a law which you knew should never have existed, a law which you knew was evil. You would become an accomplice of the evil of the writers of that law. But you did have a choice, a choice protected from all reprisals by an ancient and fundamental legal tradition. The choice was yours alone.
Law is notoriously complex.
You may wonder if ordinary men are competent to judge it. The point of having laws is to know what is allowed and what is forbidden. The juror must therefore judge it unjust, and vote not guilty as a matter of moral obligation. Finally, a law which is generally just may impose injustice in a particular case. This is the situation in which judges may fine someone one cent, and give him 99 years to pay it.