Witness Protection Act Article 20

The judge has discretion not to hold a public trial if the judge consider the public trial would put the life, body or freedom of the protected witness in jeopardy.
中文原文 證人保護法第20條
訴訟之辯論,有危害證人生命、身體或自由之虞者,法院得決定不公開。

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