Psychiatric defense，也称insanity defense,翻译为“精神病辩护”，是一个英美法术语，指的是承认刑事指控所述的行为，但提出行为人精神失常不负刑事责任的辩护。

英美国家刑事诉讼精神病辩护的证明原则大致有四种：①姆纳顿规则M'Naghten Rule，②无法控制规则Irresistable Impulse Rule，③德拉姆规则Durham Rule，④实际能力规则Substantial Capacity Rule。

参考双语例句：

The idea behind permitting the insanity defense is essentially that an individual is only deserving of punishment for a crime if he or she is capable of understanding the difference between right and wrong. Since it is believed that an insane person is incapable of making sound decisions, many believe such defendants should not be liable for their crimes.

允许进行精神错乱辩护本质上是因为，个人只有在有能力理解是非对错时才应该对所犯罪行负责并接受相应处罚。人们普遍认为一个精神错乱的人是无法做出正确理智的判断的，因此有该情况的被告可免除对所犯罪行的处罚。