affirmative defense | Definition

Doc's CJ Glossary by Adam J. McKee
Course: Criminal Law

An affirmative defense is a justification for the defendant having committed the accused crime, such as self-defense or duress.


In the context of criminal law, an affirmative defense is a legal argument used by the defendant to justify their actions and to avoid criminal liability for the charged offense. An affirmative defense acknowledges that the defendant did commit the act they are accused of but argues that they had a valid reason for doing so.

The term affirmative in this context means that the defendant has the burden of proving their defense by presenting evidence and convincing the judge or jury that their actions were justified under the law.

The term defense refers to the legal argument used by the defendant to counter the prosecution’s case. The defense may argue that the prosecution has not met its burden of proof or that the defendant’s actions were justified under the law.

In the criminal justice system, the term affirmative defense is used to distinguish these types of defenses from other types of defenses, such as denial of guilt, which involves the defendant denying that they committed the crime at all. Affirmative defenses, on the other hand, acknowledge that the defendant did commit the act they are accused of but offer a justification or excuse for their behavior.

The use of affirmative defenses in criminal law can be traced back to the common law legal system, which developed in England during the Middle Ages. Under common law, the defendant was required to present an affirmative defense to counter the prosecution’s case and the burden of proof rested with the defendant.

Today, affirmative defenses are a common legal strategy in criminal cases, particularly in cases where the defendant’s actions may be seen as morally or legally justified. While the burden of proof rests with the defendant, a successful affirmative defense can result in a reduction of charges or a complete acquittal.

One of the most well-known examples of an affirmative defense is self-defense. In cases of self-defense, the defendant admits that they used force or violence against another person but argues that their actions were necessary to protect themselves from harm. The defendant must show that they had a reasonable belief that they were in danger of bodily harm or death and that the force used was proportional to the perceived threat.

Another example of an affirmative defense is duress. In cases of duress, the defendant argues that they were forced to commit the criminal act under threat of harm to themselves or others. The defense must show that the threat was immediate and credible, that there was no reasonable way to avoid the threat other than to commit the crime, and that the defendant did not willingly participate in the criminal act.

Other examples of affirmative defenses include necessity, which argues that the defendant had no choice but to commit the crime to prevent greater harm, and consent, which argues that the victim consented to the criminal act.

It is important to note that the burden of proof for affirmative defenses rests with the defendant. In other words, the defendant must present evidence to support their defense and convince the jury that their actions were justified. The prosecution may challenge the defendant’s affirmative defense by presenting evidence to refute the claim or by arguing that the defendant did not meet the legal requirements for the defense.

If the defendant is successful in using such a defense, they may be acquitted of the charges or have their sentence reduced. However, if the defense is not successful, the defendant may be found guilty and face the full legal penalties for the charged offense.


[ Glossary ]

Last Modified: 04/29/2023

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