The above provision has originated from the principle of "no crime not punishment without law" (nullum crimen, nulla poena sine lege), which means criminal responsibility has to be in accordance wit the law prior to the commission of crime, and the punishments to be imposed upon such person also has to be provided by a provision of law, Although, heavier punishment may become possible at the later time, the court cannot punish a person more than the punishments provided by the law in force at the time the crime is committed. The rationale of the principle is to protect liberty of people, i.e., if the law makes an act which has been legal an offense in or order to punish the act committed in the past, people would not dare to do anything as they would fear that what they do might become an offense they might be punished for in the future.The same do might become an offense they might be punished for in the future. The same also applies to the punishments, people should be aware of the punishments of their act at the time of such act; it is thus unjust to increase the severity of the punishments for the act which was already committed.