Police Uniforms Act Article 3

The police shall wear the ceremonial uniform on the following occasions:1. Attending national ceremonies and banquets or those of countries with diplomatic ties with Taiwan.2. Meeting with the president or head of state with diplomatic ties with Taiwan.3. Officially visiting or paying return visits to officials or officers from countries with diplomatic ties with Taiwan.4. Attending important police ceremonies or parade inspections.On the occasion prescribed in subparagraph 4 of the preceding paragraph, the standard uniform can also be worn in lieu of the ceremonial uniform.
中文原文 警察服制條例第3條
警察人員服用禮服時間如左:
一、參加本國或友邦大典及宴會時。
二、晉謁總統或友邦元首時。
三、正式訪問或回訪友邦文武官員時。
四、參加警察各種重要典禮或校閱部隊時。
前項第四款禮服得以常服代之。

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