Right now, it feels wrong to many people because a boy who was walking home with Skittles and iced tea has ended up dead. But as lawyers say, “hard cases make bad law.” The law will always have some sad cases that can’t be prosecuted, or some cases where someone doing something understandable gets jail time for breaking the law. Laws written in response to public outcry about those hard cases are usually bad laws. They are the equivalent of deciding to give everyone an ANA test because of the tragic death of someone with undiagnosed lupus.

In both cases, we’re focusing on the emotional impact of the false negative that is right before us, and not all the other cases where false positives could be disastrous. Imagine that someone you have had words with — your editor, perhaps — attacks you, and there are no witnesses to the attack. Fearing for your life, you stab him, and he dies. Should the law require you to prove that you acted in self-defense, beyond a reasonable doubt? How could you?

Imagine now that it is a black teenager attacked by a racist 23-year-old looking for a fight, or a woman whose abusive boyfriend finally threatened to kill her. Do you want those people to have to prove that it was self-defense beyond a reasonable doubt? Should the prosecution be able to send them to prison for decades because it’s possible that they were the aggressor — not even likely, just possible? Should they have to wait until they have suffered life-threatening damage in order to justify protecting themselves?