Beviskravet vid nödvärnsinvändningar

Sammanfattning

As a general rule in Swedish law, the prosecutor bears the burden of proof for the circumstances included in the statement of the criminal act, and it must be established beyond reasonable doubt that the defendant committed the alleged act in order for the defendant to be convicted of a criminal offence. In cases involving claims of self-defence, however, a different and lower standard of proof applies. For a claim of self-defence to be considered disproven, the prosecutor must present sufficient evidence for the claim to appear unjustified. As a starting point, it is not entirely clear how this standard of proof relates to the traditional standard of proof beyond reasonable doubt. The purpose of this thesis is to examine the standard of proof applied when the prosecutor seeks to disprove a claim of self-defence, and to analyse how this standard relates to the traditional standard of proof in criminal proceed-ings. The study is based partly on a legal dogmatic analysis of legal sources and legal doctrine, and partly on a review of lower court judgments in which claims of self-defence have been assessed. In addition, the Bayesian method is applied to two model cases. The thesis initially addresses the concept of crime and the right to self-defence, as well as central issues concerning burden of proof, standards of proof, and evaluation of evidence. Particular emphasis is placed on the distinc-tion between the standard of proof beyond reasonable doubt and the lower standard applicable when the prosecutor seeks to disprove a claim of self-defence. Furthermore, the thesis discusses the Bayesian method and the use of likelihood ratios as a tool for structuring and analysing evaluation of evidence. The review of lower court judgments demonstrates that claims of self-defence are relatively rarely successful. Of the 50 most recent judgments in which a claim of self-defence was examined, the courts found that a right to self-defence existed in 16 per cent of the cases. A more in-depth review of 60 judgments reveals the following. Witness superiority in favour of the defend-ant, essentially, always means that the prosecutor fails to disprove the claim of self-defence. A balance in witness evidence most often – though not always – means that the prosecutor fails to disprove the claim of self-defence. Witness superiority in favour of the prosecutor most often – though not always – means that the prosecutor succeeds in disproving the claim of self-defence. When the Bayesian method is applied, likelihood ratios are calculated for two model cases. The study indicates that a likelihood ratio of 4 is insufficient for the prosecutor to disprove the claim of self-defence, whereas a likelihood ratio of 9 is sufficient.