I discovered a new podcast, The Life of the Law. It is similar in style to 99% Invisible. On their first podcast they discussed the concept of jury nullification.
When a jury nullifies, it finds a defendant not guilty, although the jurors may actually believe he is guilty. And because it’s illegal to retry someone, the person goes free. Jury nullification happens when jurors don’t agree with a law, or think there should be an exception.