Assembly and Parade Act Article 24

When an assembly or parade is in progress, the police may be present on the scene to maintain order.At the request of the responsible person of the assembly or parade, the competent authority shall have officers be present on the scene to regulate traffic and maintain order.
中文原文 集會遊行法第24條
集會、遊行時,警察人員得到場維持秩序。
主管機關依負責人之請求,應到場疏導交通及維持秩序。

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