Related Rule
Finland
Practice Relating to Rule 101. The Principle of Legality
In 2003, in its fifth periodic report to the Human Rights Committee, Finland stated:
230. The principle of legality in criminal law (nullum crimen sine lege) is provided for in section 8 of the Finnish Constitution, according to which no one shall be found guilty of a criminal offence or be sentenced to a punishment on the basis of a deed, which has not been determined punishable by an Act at the time of its commission. The penalty imposed for an offence shall not be more severe than that provided by an Act at the time of commission of the offence.
231. The corresponding obligations in Article 15 of the Covenant [1966 International Covenant on Civil and Political Rights] and in Article 7, paragraph 2, of the European Convention on Human Rights, respectively, are absolute. The reference to human rights conventions in section 23 of the Finnish Constitution means that derogation from the provisions of Article 15 is not possible, not even in exceptional situations.
232. In the spring of 2003, in connection with the reform of the Penal Code, specific provisions on the principle of legality and temporal restrictions as to the application of the penal provisions, were added to the Penal Code. The new provisions are scheduled to enter into force at the beginning of 2004. According to the new provisions in section 1 of Chapter 3 of the Penal Code, no one shall be held guilty of any criminal offence on account of any act or omission which did not constitute a criminal offence at the time of its commission. The sentence or any other criminal law sanction must be based on law. New section 2 in the same Chapter concerns the temporal restrictions, providing, inter alia, for the principle of the lighter penalty referred to in Article 15. However, the relevant bills (HE 44/2002) passed already by Parliament are still waiting for approval of the President of the Republic. 
Finland, Fifth periodic report to the Human Rights Committee, 24 July 2003, UN Doc. CCPR/C/FIN/2003/5, submitted 17 June 2003, §§ 230–232.
In 2006, in a report to the Counter-Terrorism Committee of the UN Security Council, Finland stated: “According to the Constitution of Finland, no one shall be found guilty of a criminal offence or be sentenced to a punishment on the basis of a deed which has not been determined punishable by an Act at the time of its commission.” 
Finland, Report to the Counter-Terrorism Committee of the Security Council in response to its questions on Finland’s implementation of the provisions of resolution 1624(2005) presented in its letter of 15 May 2006, enclosure to Letter dated 14 July 2006 from the permanent representative of Finland to the United Nations addressed to the Chairman of the Counter-Terrorism Committee, annexed to UN Doc. S/2006/506, 19 July 2006, Letter dated 17 July 2006 from the Chairman of the Security Council Committee established pursuant to resolution 1373 (2001) concerning counter-terrorism addressed to the President of the Security Council, p. 7.