Noun
(literally) A wrong in itself; that which is injurious in its consequence.
(law) The Latin phrase used in law to refer to crimes that are illegal from the nature of crime, that is, inherently evil without any fact of being noticed or punished, as opposed to malum prohibitum. Used to develop common law crimes.
Source: en.wiktionary.orgThe courts used the concept of malum in se to develop various common law offences. Source: Internet
They regard a "crime malum in se" as inherently criminal; whereas a "crime malum prohibitum" (the argument goes) counts as criminal only because the law has decreed it so. Source: Internet