The Motion Picture Act Article 6

When imported foreign motion pictures have caused or might cause severe damage to domestic motion picture enterprises, to sustain and develop domestic motion picture enterprises, the central competent authority may establish temporary measures to protect the cultural subjectivity of domestic motion pictures such as establishing a minimum percentage of films being screened that must be domestic motion pictures.
中文原文 電影法第6條
因外國電影片之進口,致我國電影事業受到嚴重損害,或有受到嚴重損害之虞時,為維護本國電影事業之存續與發展,中央主管機關得採取如設定國產電影片映演比率或其他有助維護本國電影事業文化主體性之臨時性措施。

English translation for reference only; the Chinese text prevails. Not legal advice.