This article will analyze the cause for independent directors’ limited functions by discussing the SinoPac case, which manifests the malfunction of independent directors, audit committee and the three defense lines of financial institutions. Considering that SinoPac case is not the only case in recent years, there must exist a structural issue. Due to the length restriction, this article will focus on the legislative design of independent directors. Generally speaking, the board of directors is responsible of business management, therefore, internal organization is centralized to reinforce the efficiency. Adding independent directors or audit committee into a management board will lead to a “self-supervision” dilemma and these supervisory units may not be able to compete with Chairman and internal directors. Another obstacle results from the opaqueness of independent directors’ work scope and code of conducts since clear standards for their work performance, design of authority and responsibility as well as logistics and peer support are all necessary. However, developments in society, culture and technology are evolving into a direction that benefits independent directors’ operation. Thus, if we can improve the regulatory design and supplemental measures after examining the SinoPac case, the implementation of independent directors may largely enhance the quality of corporate governance.