In a legal proceeding, whether it be civil or criminal, the plaintiff's claims can be countered by the defendant in many ways. The defendant may contest the claim and/or raise allegations against the plaintiff. He may also concede to the claims and raise any of the legal defenses, so as to avoid or lessen his liability or culpability.
A legal defense is the contention raised by the defendant, against the claims of the plaintiff. Even though the defendant counters the claims of the plaintiff, the former may admit the facts, but raise certain allegations that may avoid or lower his liability or culpability. In other words, a legal defense is the allegations made by the defendant, against the plaintiff, so that the liability of the former is excused or lessened. Affirmative defense is one such legal defense that can be raised by a defendant.
In both civil and criminal cases, the defendant can raise certain legally recognized defenses. Affirmative defense is one among them. In this type of defense, the defendant may question the veracity of the plaintiff's claim. At the same time, he discloses certain new facts that, if proved, will negate or reduce his liability or culpability. According to the 'Free Dictionary,' affirmative defense definition is stated as follows: A new fact or set of facts that operates to defeat a claim even if the facts supporting that claim are true. Even though the defendant questions the truthfulness of the claims made by the plaintiff, he admits to the act that is the cause of action. In addition to this, he raises a defense that may excuse or limit his culpability or liability.
Affirmative defense is also referred to as a justification or excuse defense, as it is used to justify the action of the defendant, that is the root cause for the legal proceeding. The defendant must raise such defense on time, and the burden of proof regarding these new facts rests on the defendant only. In other words, the defendant has to prove the facts raised by him. Affirmative defenses are applicable in both civil and criminal cases.
While contributory negligence is an affirmative defense that is commonly used in civil cases, in case of criminal law, self defense can be cited as a classic example. For instance, a pedestrian crosses the road without noticing the green signal, and gets hit by a vehicle that is driven in a negligent way. The defendant in this case (the driver of the vehicle) can raise the defense of contributory negligence, as the plaintiff himself was negligent while crossing the road.
In case of criminal culpability, self defense is a commonly used defense. If the case against the defendant is for causing bodily harm to the plaintiff, then the former may raise the affirmative defense of self defense. As per this legal defense, the defendant's action is justified with the contention that it was intended to prevent the impending injury that can be caused to him, by the plaintiff.
Apart from the above mentioned examples of self defense and contributory negligence, there are many other legal defenses that come under this category. You may come across a really long affirmative defense list, which includes defenses that are used in civil as well as criminal cases. In case of civil liability, the most common affirmative defenses are consent, estoppel, assumption of risk, accord and satisfaction, authority, fair use, repossession, waiver, merger doctrine, defense of property, and statute of limitations. In criminal cases, self defense, insanity defense, truth, statute of limitation, and necessity, are the commonly used ones.