認知神經科學於刑法體系之應用 - 以證據法為中心

Abstract

人類的「瘋狂」行為始終與人類歷史如影隨形。由於其怪異本質與一般人大相逕庭，使人類對其產生疑惑之餘，更添幾許神秘的色彩。因此，於科學蓬勃發展的近兩百多年來，許多專門領域諸如心理學、醫學、神學、神經科學、認知心理學等之研究人員，紛紛參與研究關於人類瘋狂行為之解釋。其中，以西方的演進史而言，由心理分析學派首先獨佔鰲頭，接著是精神醫學；自1980年代以降，則由認知神經科學主導關於人類腦與心之間的行為研究。

對於刑事法學而言，人類的「瘋狂」行為一旦涉及犯罪，首當其衝的則是行為人罪責判斷的問題。隨著「瘋狂」行為侵害之法益情節重大，對於罪責判斷之標準理當益發嚴密。然而，對於人類瘋狂行為之研究演進歷程，我國與西方之發展迥然不同；長久以來，直接跳過對於心理分析學派之理解，由精神醫學主導一切，無論是臨床領域，抑或是司法領域。

精神醫學於司法領域之應用，一般以精神鑑定稱之。所謂鑑定，屬於刑事訴訟程序裡關於證據之法定調查方法之一，於有鑑定必要性時由法官或檢察官方發動；而所謂鑑定必要性，係指當與案件事實具關聯性、有調查必要性、且有調查可能之證據，需仰賴特別專門知識方能予以判定。換言之，發動鑑定之目的，係為輔助法院對於案件事實與證據的了解、並基於其了解作成判斷。惟精神鑑定於實務上運行長久以來，縱使在2005年刑法第十九條修法之後，關於其實際上對於輔助法院了解事實與證據之角色，始終存在高度不確定性的問題。

如同前述提及，隨著「瘋狂」行為侵害之法益情節重大，基於踐行刑事法學追求真實、正義、與維護社會秩序之精神，對於行為人罪責之判斷，期能提供一於現行精神鑑定以外、相對客觀的鑑定意見作為法院心證形成之輔助。是故，本文以介紹認知神經科學發展、以及討論其與刑法交錯之時點為開端；接著，針對認知神經科學研究一旦作為鑑定證據時，必須先行了解其原理與可能之誤差；最後，透過美國實務上對於認知神經科學證據使用之發展與現況，對我國實務上將來引入認知神經科學證據，其使用時機、證據能力與證明力之判斷標準，提出具體建議。

The “insanity”, it has been within the human history for a long time. Due to people’s curiosity toward mysterious things, in recent hundred years, numerous researchers coming in droves from diversity scientific fields devoted themselves to explaining the cause of insanity. For instance, psychology, psychiatry, theology, neuroscience, cognitive psychology etc. were all included. In Western world, the development of the “insanity” issue was first dominated by Freud’s Psychoanalysis; then the Psychiatry; and after 1980s, the Cognitive Neuroscience has became the master stream.

In the aspect of criminal law, the insane behavior would be discussed only if there is any crime involved in it. Once the mental state of a defendant is discussed, assessing the culpability becomes the main mission of it. If the damage caused in this insanity case is pretty serious, such as murder, the culpability evaluation should be made by stricter standard, preventing the great social cost and unjust consequence. However, which is different from the insanity history in Western world, in our nation, from the beginning, the evaluation form a psychiatrist has been the main and only evidence presented in the courtroom.

In our criminal procedure system, the legitimate evidence approach for insanity case is “Forensic Psychiatry”, and the approach would proceed when the judges or prosecutors believe that there exists the need of investigation. Whenever the need of investigation is mentioned, it includes the relevancy to fact, the necessity to investigate, being possible to investigate; besides, the opinion of expertise would be needed in order to help the judges understand the evidence and make decisions. Forensic Psychiatry has been counted on for very long time; however, as a “helping hand” to the court, the actual contribution remains uncertain due to its highly subjective character, even after the amendment of Article 19 of the Criminal Law.

Accordingly, in this article, I would like to first introduce the Cognitive Neuroscience into the Criminal Law; then describe the principle of the experiment tasks of Cognitive Neuroscience; finally make a suggestive model based on the research of the Cognitive Neuroscience evidence development in the United States.