Malum in se
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A wrong in itself; an act or case involving illegality from the very nature of the transaction, upon principles of natural, moral, and public law.
Story, Ag. § 346.
An act is said to be malum in se when it is inherently and essentially evil, that is, immoral in its nature and injurious in its consequences, without any regard to the fact of its being noticed or punished by the law of the state. Such are most or all of the offenses cognizable at common law, (without the denouncement of a statute;) as murder, larceny, etc.