Every juror should know what jury nullification is, but amazingly court representatives, judges and lawyers go out of their way to try to prevent jurors from learning about this important right and responsibility.
Basically jury nullification is the right and power of a jury to find a defendent not guity even if they have technically broken the law. Many of the founders of the United States clearly wanted juries to be a safety net on laws in case lawyers and politicians go awry. Juries have the right and responsibility to filter unjust laws or the unjust application of laws. This was a strong tradition in the United State until
shortly before the civil war when northern juries started to refuse to find run-away slaves guilty of the the crime of running away from southern slave owners (most famously the Dred Scott decision). The jurors refused to unjustly condemn a man as a slave, even though the law said the slave was guilty. The right of jurors to do this was too strongly ingrained in our legal system for the lawyers to take it away, but they decided that jurors should not be informed of this right (Sparf vs US 1895).
This means that when you go to jury duty the judge almost always tells you that you must decide fact only, and only consider as law what the judge (in his jury instructions) feeds you. This is a blatent effort to manipulate juries, keep them in the dark, and deny jurors the right to judge not only fact, but law, which is the real civic duty of any good citizen juror!
The "Fully Informed Jury Association" (www.fija.org/) is a good place to learn more about this.
In actual fact, juries are famous for finding verdicts that violate the law, regardless of what instructions are given. Conclusions that are the result of passion and have no basis in the evidence presented and no justification in the law are a mainstay of juries.
Juries apparently have the right to "filter" the law, i.e. find a person not guilty even though they broke the law, and a judge can't really do much about it.
However, a jury should never invent a law, that is, return a guilty verdict because someone did something they didn't like, even though it was legal. In that case a judge can (and should) overturn the jury decision.
Juries aren't perfect. But I'm less afraid of losing civil liberties to jury rule, than under judge/lawyer/politician rule.
Rules of evidence is really interesting topic too. In general I think juries are kept too much in the dark. The Ed Rosenthal case in Oakland is a good example. Ed Rosenthal was a city employee charged with growing marijuana for the cities "medical" program. The fed's prosecuted Ed and the judge ruled that the fact that Ed was acting under city instructions was not admissible in court. The jury returned a guilty verdict. When the jury found out after the trial that Ed was a city employee many of them made very public angry statements saying they were "tricked". (Ed Rosehthal won his appeal later).
