Because we, the people, are the law. And we are free to judge one another as we ought like to be judged. And this tends to be a very good thing. If a law is so absurd as to require a law degree to begin to be able to grasp it, then it's not one anybody should ever be prosecuted for not abiding.
A related issue is jury nullification [1]. Juries cannot be forced to convict, regardless of the weight of evidence against an individual. This gives juries the ability, whether defacto or dejure, to determine whether or not a law is just. So for instance in the early 18th century New York passed a law making it a crime to criticize public officials. But with juries being unwilling to hold up the law, it had no effect. In more recent times nullification has been invoked, even if not by name, countless times in statutory rape, drug charges, etc. As wiki mentions, the recent sharp rise in hung juries (going from ~5% to 20% in recent years) has also been seen as possible evidence of a rise in jurors considering the validity or fairness of the laws they're being asked to convict others under.
Trial by jury enables a nation to express its own value system, regardless of whether or not those who happen be on top agree.
A related issue is jury nullification [1]. Juries cannot be forced to convict, regardless of the weight of evidence against an individual. This gives juries the ability, whether defacto or dejure, to determine whether or not a law is just. So for instance in the early 18th century New York passed a law making it a crime to criticize public officials. But with juries being unwilling to hold up the law, it had no effect. In more recent times nullification has been invoked, even if not by name, countless times in statutory rape, drug charges, etc. As wiki mentions, the recent sharp rise in hung juries (going from ~5% to 20% in recent years) has also been seen as possible evidence of a rise in jurors considering the validity or fairness of the laws they're being asked to convict others under.
Trial by jury enables a nation to express its own value system, regardless of whether or not those who happen be on top agree.
[1] - https://en.wikipedia.org/wiki/Jury_nullification_in_the_Unit...