反省“統計學方法”與“效率原則”在刑事證據法上的運用

On the Application of the “Statistical Methods” and the “Efficiency-principle” to the Criminal Procedural Law

由於“絕對的歷史真相”不可能被確認，自20世紀70年代開始，新證據法學派試圖以統計學的概率理論－－即貝葉斯定理－－來協助法官作出判決。首先，本文將反省貝葉斯定理是否適合用來描述審判中法官評估證據之可信度（證明力）的過程。再者，本文介紹並反省法律經濟分析學家Posner試圖運用貝葉斯定理來達成訴訟經濟之目標的策略。Posner期望借此統計學的方法，能夠使得經濟效率的追求與人權正義的保障並行不悖，獲得兩全。本文將指出，新證據法學派想用貝葉斯定理來描述法官評估證據之證明力的活動，是有困難的；而Posner又進一步想讓貝葉斯定理幫助法官同時能夠兼顧經濟與正義，他這個策略更是立足於“可預測性”這個不實的前提之上，並不具可行性，而且將導致與傳統司法價值相衝突的結果。

Because the “absolute historical fact” is inaccessible to the human understanding, New Evidence School has made use of the statistical doctrine of probability, i. e. the Bayes’ Theorem to help judges by their decision-makings. First, this essay will investigate whether the Bayes’ Theorem can adequately describe the procedure of judges’ evaluation of the credibility of evidences. Then, this essay will consider Posner’s strategy combining the Bayes’ Theorem with his Efficiency-principle for accomplishing the goal “wealth maximization” without the sacrifice of justice. The essay concludes that the application of the Bayes’ Theorem to the Evidence Law has incurred great difficulties. Besides Posner’s idea is based on the impossible precondition of “predictability” and will merely result in a serious violation of the human rights.