Chapter 3 - The general prerequisite of criminal liability
Section 2 – Temporal application
(1) The law in force at the time an offence was committed applies to the offence.
(2) However, if the law in force at the time of conviction is different from the law in force at the time of the commission of the offence, the new law applies if its application leads to a more lenient result.
(3) If the law is intended to be in force only for a fixed period of time, and there are no provisions to the contrary, the law in force at the time of the commission of the act applies to an act committed during this period.
(4) If the specific contents of a penal provision in law are determined by other provisions in law or by provisions or rules issued on its basis, the punishability of an act is assessed on the basis of the provisions or rules in force at the time of the act, unless there are provisions in law to the contrary or unless the new provisions demonstrate that the attitude towards the punishability of the act has changed.
EDIT.