Règle correspondante
Finland
Practice Relating to Rule 156. Definition of War Crimes
Finland’s Revised Penal Code (1995) provides:
A person who in an act of war
1) uses a prohibited means of warfare or weapon;
2) abuses an international symbol designated for the protection of the wounded or the sick; or
3) otherwise violates the provisions of an international agreement on warfare binding on Finland or the generally acknowledged and established rules and customs of war under public international law
shall be sentenced for a war crime. 
Finland, Revised Penal Code, 1995, Chapter 11, Section 1.
[emphasis in original]
Finland’s Criminal Code (1889), as amended in 2008, states:
Section 5 - War crime
(1) A person who in connection with a war or other international or domestic armed conflict or occupation in violation of the Geneva conventions on the amelioration of the condition of the wounded and sick in armed forces in the field, the amelioration of the condition of wounded, sick and shipwrecked members of armed forces at sea, the treatment of prisoners of war or the protection of civilian persons in time of war (Treaties of Finland 8/1955, Geneva conventions) or the additional amendment protocols … to the Geneva conventions, on the protection of victims of international armed conflicts and the protection of victims of non-international armed conflicts (Treaties of Finland 82/1980, I and II protocols) or other rules and customs of international law on war, armed conflict of occupation, [commits one of the offences enumerated in Section 5(1)],
shall be sentenced for a war crime to imprisonment for at least one year or for life.
(2) Also a person who commits another act defined under article 8 of the Rome Statute of the International Criminal Court (Treaties of Finland 56/2002) or in another manner violates the provisions of an international agreement on war, armed conflict or occupation that is binding on Finland or the generally recognized and established laws and customs of war in accordance with international law shall be sentenced for a war crime.
(3) An attempt is punishable.
Section 6 - Aggravated war crime
(1) If the war crime is committed as part of a plan or policy or as part of extensive war crimes and
(1) the offence is directed against a large group of persons,
(2) the offence causes very serious and extensive damage,
(3) the offence is committed in an especially brutal, cruel or degrading manner, or
(4) the offence is committed in an especially planned or systematic manner,
and the offence is aggravated also when assessed as a whole, the offender shall be sentenced for an aggravated war crime to imprisonment for at least eight years or for life.
(2) An attempt is punishable.
Section 7 - Petty war crime
(1) If the war crime, considering the consequence caused or the other relevant circumstances, is petty when assessed as a whole, the offender shall be sentenced for a petty war crime to a fine or to imprisonment for at most two years.
(2) An attempt is punishable. 
Finland, Criminal Code, 1889, as amended in 2008, Chapter 11, Sections 5–7.
[emphasis in original]