Enforcement Rules for State Compensation Law Article 7

The claimant may authorize an agent to negotiate with the liable compensating authority on behalf of him. Where there are several claimants involved in a legal relation, one or several agents may be authorized among the claimant to negotiate with the liable compensating authority.The agents referred to in the preceding paragraphs shall present the authorization documents in the beginning of the negotiation.
中文原文 國家賠償法施行細則第7條
請求權人得委任他人為代理人,與賠償義務機關進行協議。
同一損害賠償事件有多數請求權人者,得委任其中一人或數人為代理人,與賠償義務機關進行協議。
前二項代理人應於最初為協議行為時,提出委任書。

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