Nullum crimen nulla poena sine lege is a Latin phrase that translates to “no crime no penalty without law”
This is a legal principle that for a crime to be made out and for punishments to be meted out for that crime, there has to be a law in place. This principle stems from the concept of the rule of law.
In Singapore, this legal principle is codified into Article 11(1) of our Constitution:
11. – (1) No person shall be punished for an act or omission which was not punishable by law when it was done or made, and no person shall suffer greater punishment for an offence than was prescribed by law at the time it was committed.
This also prevents a person from being charged with an offence that was not an offence made out by statute at the time of the act.
As Singapore is a common law country, “the courts are also precluded from retrospectively reversing a previous interpretation of a criminal statutory provision where the new interpretation creates criminal liability for the first time, and where it would operate to the prejudice of an accused.” (See Public Prosecutor v Manogaran s/o R Ramu  SGCA 64 at )