jury nullification

noun
  1. : the acquitting of a defendant by a jury in disregard of the judge's instructions and contrary to the jury's findings of fact

    Note: Jury nullification is most likely to occur when a jury is sympathetic toward a defendant or regards the law under which the defendant is charged with disfavor. Except for a statutory requirement to the contrary, a jury does not have to be instructed on the possibility of jury nullification.