He escaped a prison sentence by reason of unsound mind at the time the crime was committed.
他以犯罪时精神不正常为由逃过了监禁刑罚。
原声例句
幽谷百合(上)
I had the happiness of at last seeing her take the reins in hand and govern that unsound mind.
我很高兴终于看到她掌管着那颗不健全的头脑。
英语百科
Mental disorder
A mental disorder, also called a mental illness or psychiatric disorder, is a diagnosis of a behavioral or mental pattern that can cause suffering or a poor ability to function in ordinary life. Such features may be persistent, relapsing and remitting, or occur as a single episode. Many disorders have been described, with signs and symptoms that vary widely between specific disorders.