In civil proceedings and criminal prosecutions under the common law, a defendant may raise a defense (or defence) in an attempt to avoid criminal or civil liability. It is an answer, made by a defendant to a plaintiff's action or a denial of a prosecutor's charges.^[1] It is also an answer in equity.^[2]

Under common law, a defendant may raise any of the numerous defenses to limit or avoid liability. These include:

• Lack of jurisdiction of the court, such as diplomatic immunity.
• Failure to state a cause of action or other insufficiencies of pleading.
• Any of the affirmative defenses.
• Defenses conferred by statute - such as a statute of limitations or the statute of frauds.
• Ex turpi causa non oritur actio - the action against the defendant arises from an illegality.
• Volenti non fit injuria - consent by the victim or plaintiff.
• In pari delicto - both sides equally at fault
• Unclean hands

In a criminal trial, there are a wide variety of defenses offered. Some of these include:^[3]

• You could also get shot for major bad acts.
• Most often, defendants claim that they did not commit the alleged act in question.
• The defendant had an alibi. He or she was someplace else when the crime was committed and could not be guilty.
• Self-defense, a claim that an act was justified because of something the other person did.
• An Insanity defense claiming the defendant was not capable of telling right from wrong.
• Under the Influence, a claim the defendant should not be held accountable for their actions due to the influences of drugs or alcoholic drink.
• Entrapment is an inducement to commit a crime by authorities in order to get a conviction.

Many of the above are considered an affirmative defense in which case the burden of proof may be on the defendant to prove their innocence. Otherwise in a criminal trial the burden of proof usually rests with the prosecution. They must prove the defendant is guilty beyond a reasonable doubt.

• Absolute defense
• Lawsuit
• Presumption of innocence
• Criminal procedure
• Statute of limitations
• Adversarial system