4. LIABILITY TO TRIAL.

No person is liable to be tried or punished in Papua New Guinea for an indictable offence except under the express provisions of the Code or some other Act of the Parliament.

SCHEDULE 1 – THE CRIMINAL CODE.

PART I. – INTRODUCTORY.

Division 3. – Application of the Criminal Law.

11. EFFECT OF CHANGES IN LAW.

(1) A person cannot be punished for doing or omitting to do an act unless–

(a) the act or omission constituted an offence under the law in force when it occurred ; and
(b) doing or omitting to do the act under the same circumstances would constitute an offence under the law in force at the time when he is charged with the offence.

(2) If the law in force when the act or omission occurred differs from that in force at the time of the conviction, the offender cannot be punished to any greater extent than was authorized by the former law, or to any greater extent than is authorized by the latter law.

Article 23
Nulla poena sine lege
A person convicted by the Court may be punished only in accordance with this Statute.