Code of Civil Procedure Article 54
A third person may intervene to assert a claim against the parties to an action pending in a court of either the first or second instance under any of the following circumstances:1.When such third person asserts rights to the whole or a part of any claim of the action;2.When such third person claims that the outcome of the action will infringe its rights.The provisions of all subparagraphs of Article 56 shall apply mutatis mutandis to an action initiated in accordance with the provision of the preceding paragraph.
中文原文 民事訴訟法第54條
就他人間之訴訟，有下列情形之一者，得於第一審或第二審本訴訟繫屬中，以其當事人兩造為共同被告，向本訴訟繫屬之法院起訴：
一、對其訴訟標的全部或一部，為自己有所請求者。
二、主張因其訴訟之結果，自己之權利將被侵害者。
依前項規定起訴者，準用第五十六條各款之規定。
一、對其訴訟標的全部或一部，為自己有所請求者。
二、主張因其訴訟之結果，自己之權利將被侵害者。
依前項規定起訴者，準用第五十六條各款之規定。