Jury Nullification: The Jurisprudence of Jurors' Privilege - Hardcoverby Travis Hreno (Author) Jury nullification, in its simplest definition, occurs when a jury returns a not guilty verdict for a defendant it believes to be legally guilty of the crime charged. To put this explicitly, a jury nullifies when, despite believing both a) that the defendant did, beyond a reasonable doubt, commit the act omission in question, and b) that such behavior is, in fact, prohibited by law, nevertheless declares the defendant