What is an affirmative defense in the context of criminal law?

An affirmative defense in criminal law is a type of defense strategy where the defendant acknowledges the acts committed but presents a justification or excuse that may provide legal grounds for avoiding liability. In such cases, the prosecution does not carry the burden of disproving the defendant's claims. Instead, it is the responsibility of the defendant to present evidence supporting this defense.

When an affirmative defense is offered, and if the jury finds the presented evidence credible, they may acquit the defendant, despite the prosecution's evidence of guilt. Examples of affirmative defenses include self-defense, insanity, and duress, among others. The fundamental aspect is that even if the prosecution proves its case beyond a reasonable doubt, the defendant can still avoid liability if the affirmative defense is upheld. Understanding this concept is crucial as it highlights the dynamics of burden of proof between the prosecution and defense in a criminal trial.