Mistake of Legal Element, the Common Law, and Article 32 of the Rome Statute: A Critical Analysis

Abstract

Article 32(2) of the Rome Statute provides that "[a] mistake of law may... be a ground for excluding criminal responsibility if it negates the mental element required by such a crime." Although this provision has been described as "cryptic," I argue in this essay that it was specifically drafted to exculpate what common-law scholars have variously called "mistake of mixed fact and law," "mistake of legal fact," and - most usefully - "mistake of legal element": namely, a mistake regarding the definition of a legal element in a crime. A perpetrator who commits a mistake of legal element (MLE) cannot be said to have acted "knowingly" with regard to that element, and is thus entitled to an acquittal if the element requires knowledge. The war crime of attacking a civilian population, for example, requires the perpetrator to know that the population in question qualifies as civilian under international humanitarian law. A perpetrator who honestly but incorrectly believes that a population forfeits its civilian status if soldiers are present within it, therefore, commits an exculpatory MLE.

Most international criminal law scholars accept the idea that at least some MLEs are exculpatory under Article 32. At the same time, however, they insist that few MLE defenses will be successful. I disagree, for three reasons. First, nearly every crime in the Rome Statute contains at least one legal element; the "civilian" element alone, for example, appears in 16 different war crimes. Second, the two methods that the drafters of the Elements of Crimes used to limit MLEs - providing that legal elements only require knowledge of the underlying facts and replacing Article 30's default knowledge requirement with a simple negligence standard - are almost certainly inconsistent with the Rome Statute. Third, all of the mechanisms that scholars have proposed to limit MLEs - such as subjecting them to German criminal law's "layman's parallel evaluation" test or requiring them to be reasonable - are inconsistent with Article 32's common-law principles.

Keywords: international criminal law, international humanitarian law, Rome Statute, International Criminal Court, ICC, common law, civil law, mistake, substantive criminal law, criminal defenses, mens rea, mental states