Sannolikhetslära och juridik - en perfekt match?

Sammanfattning: There have been claims put forth which aims at proving that the theories developed within mathematics, but also within economics to name one, regarding decision making and fact finding would suit very well to be adopted into the legal decision making as well. It is in this context primarily Bayes’ theorem which is referred and mentioned theorems compatibility with law. One of the first articles regarding this matter was an article written by John Kaplan in the late sixties. Bayes’ theorem is applicable whenever the probability of a hypothesis is to be determined by someone who is gradually presented with more and more evidence, which to some degree speak to the truth of the hypothesis. Bayes’ theorem also constitutes how one is supposed to reason, which aspects to consider and so on, when a value is to be put on any given evidence. Mentioned theorem seems, at first glance, to be perfectly suited for legal matters. But to investigate this matter further it is fundamental to examine what the legal decision making encompasses. There are of course also those who claim that Bayes’ theorem actually not at all is suited for legal decision making, since it is mathematics and mathematics have nothing to do with legal matters. Furthermore, claims have been expressed that since the probability theory alone, at least not in some situations, cannot provide reason enough to convict the whole notion that probability theory has a place in law should be disregarded. Some of the arguments against the incorporation of Bayes’ theorem have been expressed as paradoxes. Probability theory has been on the agenda for discussion in other scientific disciplines as well. A principally identical discussion was held within the scientific genre of physics from the thirties and forward. It is the controversial aspect of physics known as quantum physics that is meant. This discussion must be considered to have been won by the advocators of probability theory, since quantum physics today is considered a legitimate scientific field. In the ongoing analysis the statements made in the literature regarding the application of probability theory to law is problematised. Several of the most essential aspects are readily analyzed. After a closer look at the questions at hand, and the arguments made from both sides, it is impossible to deny that probability theory in theory would be a perfect match for legal decision making. There are, although, a number of practical problems, which must be addressed.