The victim simply drank too much and walked into the wrong house at night - getting himself shot by an angry, armed homeowner, who consciously decided to shoot first and investigate later. Absent jury nullification, if convicted, Mr. Citizen would mandatorily spend six years in the Illinois Department of Corrections. Using jury nullification, this defendant would at least have a chance of being found not guilty. Historically, governments have often passed stupid laws. Judges lack the authority to rewrite bad legislation.
Prosecutors are sometimes under pressure to enforce bad laws - even stupid and unethical laws.
A glaring, real-life example is the current, criminal prohibition against medical doctors assisting terminal patients with their pitiful attempts at suicide. The State of Michigan insists that this practice is evil and has made it a felony. At least one prosecutor has made it his cause celebre. But Michigan jurors are not buying into this legal determination by the government of Michigan. Finally, lest we forget, slavery was once legal in the United States.