Assembly and Parade Act Article 15

In case of natural disasters or serious accidents after an outdoor assembly or a parade is approved; the competent authority shall revoke the permit or change the originally approved time, place, route, or restrictions for the urgent necessity to maintain social order and public interests. In any of the conditions as prescribed in subparagraphs 1 to 6 of Article 11, the permit shall be revoked or canceled.The revocation, cancelation, or change prescribed in the preceding paragraph, shall be specified in writing and notified to the responsible person prior to the assembly or parade being held. The same shall apply if an assembly or parade is in progress.
中文原文 集會遊行法第15條
室外集會、遊行經許可後,因天然災變或重大事故,主管機關為維護社會秩序、公共利益或集會、遊行安全之緊急必要,得廢止許可或變更原許可之時間、處所、路線或限制事項。
其有第十一條第一款至第六款情事之一者,應撤銷、廢止許可。
前項之撤銷、廢止或變更,應於集會、遊行前以書面載明理由,通知負責人;集會、遊行時,亦同。

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