The Criminal Speedy Trial Act Article 8

A case shall not be appealed to the Supreme Court if it is more than six years from the date the case is pending in the first instance and after being remanded by the Supreme Court for the third time, the court of second instance upholds the not guilty judgement rendered by the first instance or its not guilty judgement has been upheld by courts of the same instance for more than twice before remanding.
中文原文 刑事妥速審判法第8條
案件自第一審繫屬日起已逾六年且經最高法院第三次以上發回後,第二審法院更審維持第一審所為無罪判決,或其所為無罪之更審判決,如於更審前曾經同審級法院為二次以上無罪判決者,不得上訴於最高法院。

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