He was charged with murder, but got off on a plea of insanity.

他被指控犯了谋杀罪，但以精神错乱为由逃过惩罚。

《牛津词典》

I also think we must do something about the insanity plea.

我还认为我们必须对疯狂的抗辩采取行动。

youdao

Phillips murdered his wife, but got off on a plea of insanity.

菲利普斯谋杀了自己的妻子，但以精神错乱为由逃脱了罪责。

《柯林斯英汉双解大词典》

Last week, defense attorneys publicly acknowledged for the first time that they were considering an insanity plea.

NPR: Colo Shooting Suspect Was Hospitalized, Restrained

An insanity plea is at the intersection of law and psychology or psychiatry.

FORBES: Holmes Wants to Plead Insanity For Colorado Theater Shooting. What Does Insanity Mean?

But an insanity plea could make such a move harder, said David Beller, an attorney who is not connected to the case.

CNN: Judge enters not guilty plea for accused theater shooter