The trial jury created by our Constitution is a judicial body with more power than Congress, the President, or even the Supreme Court. Judges frequently say the "issue of law" is for them to determine, and instruct the jury to rule only on the fact of whether a defendant broke the law. But a jury has the power to decide the issues of law under
which the defendant is charged, as well as the facts. American juries have a proud tradition of standing up and saying "no" to oppressive, unjust laws. In our system of checks and balances, the jury is the conscience of the community and the final arbiter of justice.
In an American courtroom, there are, in a sense, 12 additional judges, beside the one with the gavel. As the U.S. Fourth Circuit Court of Appeals ruled in 1969, "If the jury feels that the law under which the defendant is accused is unjust, or that exigent circumstances justified the actions of the accused, or for any reason which appeals to their logic or passion, the jury has the power to acquit, and the courts must abide by that decision."
Just as police use discretion on when to enforce the law, and prosecutors use discretion when charging someone, and judges use discretion in deciding whether to dismiss those charges, jurors also have the power to use their discretion in applying the law. If a law is unjust as applied to a case, jurors may vote to acquit.
Jurors must know their rights because, once selected for jury duty, no one will inform them of their power to judge both law and fact. The judge's instructions to the jury may even be to the contrary. Jurors—armed with the knowledge of their real rights, powers and duties—can, with their single vote of "not guilty," hang a jury. It may not be an acquittal, but it will prevent an unjust conviction. Jurors’ power keeps our government in check. For more info, see fija.org.