SkillsUSA Criminal Justice Practice Test 2026 - Free Criminal Justice Practice Questions and Study Guide

An affirmative defense is one that admits to the commission of a criminal act but argues that there is justification or a valid legal reason for the action taken. Self-defense, insanity, and necessity are all accepted affirmative defenses that can potentially absolve a defendant from criminal liability under specific circumstances.

Self-defense involves acting to protect oneself from imminent harm; insanity relates to a defendant's mental state at the time of the crime; necessity justifies actions taken to prevent greater harm.

In contrast, claiming duress does not fall under the category of an affirmative defense in the same way the others do. It typically argues that the defendant was compelled to commit the crime due to the immediate threat of harm from another, suggesting a lack of free will rather than a justification for the crime. Thus, it is considered a defense, but not an affirmative one that admits to the act while providing justification.