To prove someone committed a crime, the state (through its prosecutors) must prove beyond a reasonable doubt that the defendant committed each element of the crime. Therefore, defenses to any crime start with negating one or more of the elements of the crime. Additionally, some crimes allow for "affirmative" defenses which, if the defendant can prove the defense applies, will result in a verdict of "not guilty" even if the prosecutor proves the defendant met each of the elements of the crime.
For Mayhem, convincing the jury that the prosecutor failed to prove beyond a reasonable doubt that the defendant acted willfully or maliciously, caused serious bodily injury, etc. would be enough to get a not guilty verdict.
If the prosecutor can prove all the elements of Mayhem, however, the defendant must prove that one or more justifications for his actions existed (i.e., it is the defendant's burden to prove an affirmative defense). For Mayhem, some of these justifications include:
- Defense of another;
- Duress / Threats;
- Entrapment; and
- Statute of Limitations.