Sometimes, defendants will concede that the prosecution has proved every element of the charged crime, but will offer reasons why they should not be convicted. These reasons are called “affirmative defenses,” and they include claims of self-defense, necessity, insanity, and so on. For example, a murder charge requires the prosecutor to prove three things: that the defendant 1. killed, 2. another person, 3. with the intent to do so. Defendants may concede all three issues, but argue that the killing was justified as an act of self-defense.
When self-defense is at issue, it’s up to the defendant to produce evidence, obviously. But what happens next? Here’s where things get tricky.
•In some states, once the defense has produced the evidence, it’s up to the prosecution to disprove beyond a reasonable doubt the truth of the defense.
•In other states, the defendant has not only the burden of producing evidence, but the burden of persuasion as well. In these states, the defense must prove the validity of its claim by a standard less rigorous than “beyond a reasonable doubt,” known as proof by a “preponderance of the evidence.”