Mistake of fact 事实（上的）错误（包括将实际不存在的事物误认为存在，或将重要事实因无意识、不知情、健忘等原因而误认为不存在。事实错误如果涉及欺诈或合同的实质内容而非细节可作为修改或撤销合同的依据，不论该合同是否已履行。）

“Mistake of fact” generally refers to a mistaken understanding by someone as to the facts of a situation—the mistake results in the person committing an illegal act. Mistake of fact is a defense to a crime where the mistaken belief, if it were true, would negate a mental state that’s an element of the crime. 以下为相关例句，可供参考：

For example, using the pronoun he in reference to judges is both a mistake of law and liable to offend some of your readers (not to mention some present and former justices of the U.S. Supreme Court).

例如，使用代词“he ”代替法官，不仅是事实错误，还会得罪一些读者，更不必说美国最高法院前任或现任的大法官。

Mistake of law法律（上的）错误（指了解全部事实而就其法律后果得出错误的结论，即对事实的不全面或不正确判断而形成的错误意见或推断。掌握全部事实并得出正确结论，这就是法律原则的正确适用，推定为人人皆知，称作“法律”。掌握事实而得出错误结论是法律原则的错误适用，称作“法律上的错误”。）

Mistake of law is a legal principle referring to one or more errors that were made by a person in understanding how the applicable law applied to their past activity that is under analysis by a court. In jurisdictions that use the term, it is differentiated from mistake of fact. 以下为相关例句，可供参考：

Because criminal procedure law has the unique characteristics of Protection of Human Rights, it is more important and significant to remedy mistake of law in the adjudication.

由于刑事诉讼法所特有的“人权保障法”性质,使得对于裁判中法律错误的救济更具有重要的作用和意义。

相关知识拓展：There is a principle of law that "ignorance of the law is no excuse". In criminal cases, a mistake of law is not a recognized defense, though such a mistake may in very rare instances fall under the legal category of "exculpation". In criminal cases a mistake of fact is normally called simply, "mistake". 如：

The mistake of expectant possibility includes not only mistake of law, but also mistake of fact.

期待可能性错误既包括法律错误，也包括事实错误，是一种独立的错误类型。