The punishment imposed shall not be more severe than that prescribes by the law in force at the time the act is committed. But if the subsequent law, which replaced the law in force at the time the offense was committed, is more favorable to the offender than the law it replaced, the more favorable provision shall be applied retrospectively, according to Section 6. The rationale of this principle is that the act is now regarded a less serious crime under current law, thus, it becomes unreasonable to impose the offender a more severe punishment under the replaced law.