Family Act Article 48
A final and binding judgment on a family-matter litigation concerning matters belonging to Category A or Category B in accordance with Article 3 shall be legally binding on a third party. Nonetheless, the foregoing provision shall not apply to the following situations:1. where a party whose marital relations will be affected by the outcome of litigations on a declaratory judgment on confirming the invalidity of a marriage, or on a judgment of the existence or non-existence of a marriage has been prevented from intervening in the action prior to the conclusion of the oral argument proceedings for the first or second instance due to reasons not imputable to himself or herself;2. where a party who would assert that he or she has a parental relation with a child in question depending on the outcome of a litigation on a declaratory judgment on confirming the existence or non-existence of a parental relation has been prevented from intervening in the action prior to the conclusion of the oral argument proceedings for the first or second instance due to reasons not imputable to himself or herself;3. where a child born out of wedlock who would assert that he or she be affected by the outcome of a litigation on acknowledgement of a child has been prevented from intervening in the action prior to the conclusion of the oral argument proceedings for the first or second instance due to reasons not imputable to himself or herself.Where a party provided in Subparagraphs 1 to 3 of the preceding paragraph or a third party whose interest of a legal nature is involved has been prevented from intervening in the action due to reasons not imputable to himself or herself, such a party may initiate an opposition action against the final and binding judgment to seek the revocation of the part of the judgment in question which is prejudicial to his or her interest. Provisions in PART V-I of the Code of Civil Procedure on third-party opposition proceeding shall apply, mutatis mutandis, to the foregoing circumstances.
中文原文 家事事件法第48條
就第三條所定甲類或乙類家事訴訟事件所為確定之終局判決，對於第三人亦有效力。
但有下列各款情形之一者，不在此限：
一、因確認婚姻無效、婚姻關係存在或不存在訴訟判決之結果，婚姻關係受影響之人，非因可歸責於己之事由，於該訴訟之事實審言詞辯論終結前未參加訴訟。
二、因確認親子關係存在或不存在訴訟判決之結果，主張自己與該子女有親子關係之人，非因可歸責於己之事由，於該訴訟之事實審言詞辯論終結前未參加訴訟。
三、因認領子女訴訟判決之結果，主張受其判決影響之非婚生子女，非因可歸責於己之事由，於該訴訟之事實審言詞辯論終結前未參加訴訟。
前項但書所定之人或其他與家事訴訟事件有法律上利害關係之第三人，非因可歸責於己之事由而未參加訴訟者，得請求撤銷對其不利部分之確定終局判決，並準用民事訴訟法第五編之一第三人撤銷訴訟程序之規定。
但有下列各款情形之一者，不在此限：
一、因確認婚姻無效、婚姻關係存在或不存在訴訟判決之結果，婚姻關係受影響之人，非因可歸責於己之事由，於該訴訟之事實審言詞辯論終結前未參加訴訟。
二、因確認親子關係存在或不存在訴訟判決之結果，主張自己與該子女有親子關係之人，非因可歸責於己之事由，於該訴訟之事實審言詞辯論終結前未參加訴訟。
三、因認領子女訴訟判決之結果，主張受其判決影響之非婚生子女，非因可歸責於己之事由，於該訴訟之事實審言詞辯論終結前未參加訴訟。
前項但書所定之人或其他與家事訴訟事件有法律上利害關係之第三人，非因可歸責於己之事由而未參加訴訟者，得請求撤銷對其不利部分之確定終局判決，並準用民事訴訟法第五編之一第三人撤銷訴訟程序之規定。