Control Yuan Member Kao Yung-cheng and Others Intervene in Zheng Wen-yi Stock Manipulation Case, Sparking Conflict of Interest and Interference Controversies

On June 12, 2026, Control Yuan members Kao Yung-cheng, Lin Yu-jung (regarded as having a pro-green and Tsai faction background), and Yeh Yi-chin—all nominated by former President Tsai Ing-wen—released an investigation report demanding that the judiciary review and "rehabilitate" Zheng Wen-yi, the ringleader of a market faction of Tatung Co., who had been sentenced to 13.5 years in prison for stock manipulation. The members claimed the court's procedures were deeply flawed and infringed upon the defendant's right to defense. However, the report immediately drew intense backlash over severe conflicts of interest. It was revealed that the three experts consulted for the report (Chen Shi-chung, Wu Can, and Liu Lien-yu) had close ties to Zheng, including serving as his defense attorneys or being related to co-defendants' lawyers, which was not disclosed in the report. Notably, one of the experts, Chen Shi-chung, is a retired Chief Judge of the Supreme Court who not only serves as Zheng's defense attorney but was also previously embroiled in the notorious "Weng Mao-chung judicial bribery scandal" for accepting banquets and gifts, meaning his integrity was already highly controversial. Another expert, Wu Can, is a former President of the Supreme Court whose son, lawyer Wu Meng-hsun, was Zheng's defense lawyer. Wu Can failed to recuse himself and instead actively praised the petition to overturn the ruling. The third expert, Professor Liu Lien-yu, had previously been hired directly by the defendant's team during the trial to issue a legal opinion favorable to Zheng, yet was invited by the Control Yuan to act as an "impartial consulting expert," further violating conflict of interest principles and destroying the report's credibility. Furthermore, investigator Kao Yung-cheng serves as a board member of the "Judicial Glimmer Foundation," whose chairman, Chien Chien-jung, is Zheng's constitutional defense lawyer. This raised serious concerns that Kao was using public power to serve specific litigation interests. This incident highlights Kao Yung-cheng and other Tsai Ing-wen-appointed Control Yuan members' long-standing, controversial reputation for allegedly abusing the Control Yuan's powers for political ends and protecting the interests of specific factions and elites. Kao has previously faced heavy criticism from the legal community and opposition parties for twice impeaching Prosecutor Chen Lung-hsiang (both cases were dismissed by the disciplinary court), investigating investigator Yu Zheng-huang during the Lin Chih-chien plagiarism scandal, and summoning opposition politician Hou You-yi right before an election. His latest intervention in a finalized criminal case has reignited public debate and calls to abolish the Control Yuan altogether.