The Chinese opium den and the nature of 'mala prohibita'

A LAW is malum prohibitum if it is wrong because the act is prohibited. Motive in crimes mala prohibita is immaterial. The defense of good faith is also unavailing. It is an offense that may not be inherently immoral but becomes so because its commission is declared illegal by law. It is consummated by the very fact of its performance (Colmenares v Villar, 33 SCRA 186). In acts mala in se, the intent governs but in those mala prohibita. The only inquiry is, has the law been violated?

In US vs Suy Cong Bieng, et. al. (30 Phil. 511), the Supreme Court explained the nature of offenses that are considered mala prohibita: "While it is true that... men are not and should not be held criminally responsible for acts committed by them without guilty knowledge and criminal or at least evil intent, the courts have always recognized the powers of the legislature, on grounds of public policy... to forbid in a limited class of cases the doing of certain acts; and to make their commission criminal without regard to the interest of the doer."