Defense (legal)

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. It is also an answer in equity.
Civil law defenses.
Under common law, a defendant may raise any of the numerous defenses to limit or avoid liability. These include:
Criminal defenses.
In a criminal trial, there are a wide variety of defenses offered. Some of these include:
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.