The Probability of Guilt in Criminal Cases: Are People Aware of Being 'Beyond Reasonable Doubt'?

摘要

Data from a series of studies presenting video recorded witness statements to laypersons and legal professionals were examined to trace the relationship between judged probability of guilt and the willingness to vote guilty or not guilty in hypothetical trials, in the absence of specific jury instructions. The results show that a majority of jury-eligible young and elderly participants, and police officers, were willing to convict a defendant when the judged probability of guilt exceeded .6. This is considerably below the legally accepted standard of 'beyond reasonable doubt', which usually is equated with a very high, around .9 perceived certainty. When jury deliberations were allowed, the threshold for conviction rose, approaching the standard evinced by trial judges under the same conditions. The results suggest that people prefer to vote for guilt according to a balance of probabilities principle, considering only the individual case, and disregarding the implied frequencies of false convictions.