Text of the Constitution:
12. (1) No law shall authorize the punishment of a person—
(a) for an act or omission that was not punishable by law at the time of the act or omission; or
(b) for an offence by a penalty greater than, or of a kind different from, the penalty prescribed by law for that offence at the time the offence was committed.
(2) Nothing in clause (1) or in Article 270 shall apply to any law making acts of abrogation or subversion of a Constitution in force in Pakistan at any time since the twenty-third day of March, one thousand nine hundred and fifty-six, an offence.
Meaning:
Imagine being punished for doing something that was not illegal at the time you did it, would that not be unfair to you? You are specifically protected from it under Article 12 of the Pakistani Constitution. Moreover, you cannot get a heavier penalty than what was permitted by law at the time, nor can you be punished for conduct that was not unlawful at the time. Essentially, it’s about justice, ensuring that individuals do not find themselves trapped by evolving legal frameworks. One significant limitation, however, is that this protection does not apply to anybody who attempted to overturn or destroy the Constitution after March 23, 1956. History might catch up with you in such a situation.
Application:
Let’s take the 26th amendment in the Pakistani Constitution as an example.
Let’s assume that smoking became completely illegal after the 26th amendment
in the constitution. Article 12 will protect people from getting penalised who used to smoke before the latest amendment.