Hostile M&A (Mergers and Acquisitions) often takes place when company directors & supervisors of the board are not significant shareholders. The 2015~2016 ASE-SPIL M&A case was one of the most outstanding cases in Taiwan. This thesis explores & apply in-depth analysis with viable & applicable defensive measures on the ASE-SPIL case in comparative law (United States/ Taiwan) perspectives. Alternative studies were also made to find if other feasible counter measurements were available. Comparisons & Recommendations to protect company control are also given based on scenarios in three different company cases.