. or if he or she errs regarding such a factor, the act is not intentional. Nonetheless, liability for a negligent offence may enter the question pursuant to the provisions on criminal liability for negligence. Section 2 – Mistake as to the unlawfulness of the act (515/2003) If the perpetrator errs in regarding his or her act as lawful, he or she is exempt from criminal liability if the mistake is to be deemed manifestly excusable due to the following factors: (1) the defective or erroneous publication of the law, (2) the particular obtuseness of the contents of the law, (3) erroneous advice by an authority, or (4) another reason comparable to these. Section 3 – Mistake as to a ground for exemption from liability (515/2003) If the act does not involve grounds referred to below in sections 4 through 6 which would exempt the perpetrator from liability, but such grounds would have been connected with the situation in which the act was committed as reasonably understood by the perpetrator, he or she may not be punished for an intentional offence. Nonetheless, liability for a negligent offence may enter the question pursuant to the provisions on criminal liability for negligence. Section 4 – Self-defence (515/2003) (1) An act that is necessary to defend against an ongoing or imminent unlawful attack is lawful as self-defence, unless the act manifestly exceeds what in an overall assessment is to be deemed justifiable, taking into account the nature and strength of the attack, the identity of the defender and the attacker and the other circumstances. (2) However, if the defence exceeds the limits of self-defence (excessive selfdefence), the perpetrator is exempt from criminal liability if the circumstances were such that the perpetrator could not reasonably have been expected to have acted otherwise, taking into account the dangerousness and sudden nature of the attack and the situation also otherwise. Section 5 - Necessity (515/2003) (1) An act other than that referred to above in section 4, necessary to ward off an immediate and compelling threat to a legally protected interest, is permissible as an act of necessity if the act when assessed as a whole is justifiable, taking into account the nature and extent of the interest to be rescued and the damage and detriment caused by the act, the origin of the danger and the other circumstances. (2) If the act committed in order to rescue a legally protected interest is not to be deemed permissible pursuant to subsection 1, the perpetrator is nonetheless free