Enforcement Rules of the Detention Act Article 12

To maintain order and security, a detention center may require defendants to wear specific outer clothing to facilitate identification.
中文原文 羈押法施行細則第12條
為維護看守所秩序及安全,看守所得要求被告穿著一定之外衣,以利人員辨識。

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