There are a variety of affirmative defenses that can be raised against tort actions. The affirmative defense admits the act as having taken place, but acts as an excuse for the defendant's action, and negates or lessens civil liability. Affirmative defenses are, in effect, counter-charges brought against the tortious action, sometimes implicating the plaintiff himself and, in any event, barring the plaintiff's claim completely or to a degree.
Absolute defenses bar the plaintiff's tort actions completely. Proportional defenses merely lessen the defendant's liability by the measure in which she is found at fault. A common example of an absolute defense is contributory negligence. If it can be proven that the plaintiff's own negligent actions were the result of his damages, then the defendant is not liable (unless she realized the defendant's contributory negligence and did nothing, in which case he might still recover damages). An example of a proportional defense is comparative fault, which is similar to contributory negligence in that it attempts to demonstrate that the plaintiff's own negligent actions were responsible for his damages, but different in that it attributes only partial liability to him, which means a proportion of the plaintiff's damages may be recovered. It is the responsibility of the jury in this case to determine the proportion of the plaintiff's damages are attributable to his own negligence.