現行之醫療法第79 條，限制受試者必須以「有意思能力之成年人為限」，並 設但書「顯有益於特定人口群或特殊疾病罹患者健康權益之試驗」時為其例外， 再於第2 項，針對但書之受試者，對「限制行為能力人」與「無行為能力人」兩態 樣之同意權人分別作規定。此同一規定之中卻使用「意思能力」與「行為能力」 之二不同概念作為要件，致使醫療法第79 條第1 項之「意思能力」與第2 項之「行 為能力」概念上之不連貫，連帶地使現行人體試驗之同意權人規定，即使結合人 體試驗管理辦法加以補充後，仍有多處之缺漏。 民法上之行為能力制度，係基於保護與交易安全之公示理由，將客觀上一般認為應屬「無」意思能力或是「意思能力」不足者，預設為「無行為能力人」或「限制行為能力人」，使其於法律上行為能力受限制，而不問其實施具體行為時之意思能力狀態，是以，法制上之行為能力制度設計，具有減少不確定性之功能。惟現行之行為能力制度，僅「行為能力受限者」之「意思能力」，受有「限制性」的預設，至於「具行為能力之人」之「意思能力」，並不受有「完全性」的預設，故雖為法律上所定之具行為能力之人，當其不具有健全之「意思能力」時，其法律行為仍非有效。因此，有效之法律行為，不僅須符合「行為能力」制度之規定而具有「法定行為能力」，亦須具有「健全之意思能力」，而此「意思能力」是「實施具體的法律行為時之辨識行為後果的能力」，具有「具體個別依存性」，有賴於對個案進行事實上之判斷。現行法以「有意思能力之成年人」作為受試者之原則要件，雖符民法上「意思理論」之理想，然檢討實務上作法，則發現此法規立意雖佳但並未能被落實執行，此乃因人體試驗研究者如依規定地一一確定受試者是否為「有意思能力者」，乃必須逐一為事實上之審酌，此實與民法下之行為能力制度，以制度化的方式，使其具有客觀的標準之設立本旨相違，並導致現實上發生困境。本文參酌人體生物資料庫管理條例及人體研究法之後續訂定規定，試提出以「有行為能力之成年人」或「有行為能力者」取代原規定之「有意思能力之成年人」，作為人體試驗者適格之原則規定，期能修正現行法未包含所有可能態樣之缺漏，並統整人體試驗管理辦法與醫療法，如此於實務上則可依循行為能力制度以取得受試者同意權人之同意，此具有事實上之可執行性並得以發揮保護弱勢與法律行為安全之功能。

A considerable amount of human trials has been conducted in past years and achieved profound success in Taiwan, however, the Medical Care Act (amended in 2009-5) Article 79 paragraph 1 which provided “the subjects of human research must be adults with mental capacity”, and this principle “does not apply to human research that is apparently beneficial to the health of specific population or patients with a special disease”. The latter situation should apply the paragraph 2, which provided “a person with limited disposing capacity, the consents of both the subject and his/her legal representative are required; where the research subject is a person with no disposing capacity, the consent of his/her legal representative is required.” The above regulations always led to some misunderstanding and dispute in practice because this Article confuses the concepts of ”mental capacity”, “adult”, and “disposing capacity”. This article was firstly advocated to thoroughly deliberate the concepts of “mental capacity”, “adult”, and “(disposing) capacity” in civil law, and held that the design of “disposing capacity” is to be aimed to set an easy and clear-cut threshold to limit persons from processing transaction, in order to protect the transaction security. The person possessed disposing capacity, however, does not necessarily imply intact mental capacity, which is also indispensable to make a valid expression. Consequently, this article held that the Medical Care Act Article 79 paragraph 1 should be amended as “the subjects of human research must be adults with disposing capacity” and related regulations should be also amended accordingly to correct the errors appeared in contemporary provisions. Hopefully this amendment will operate well in coordination with the “informed consent doctrine” in medical care practice and human trials.