Code of Civil Procedure Article 259
The defendant may, prior to the conclusion of the oral argument, raise a counterclaim against the plaintiff and the persons with regard to whom the counterclaim shall be adjudicated jointly in the court where the plaintiff's claim is pending.
中文原文 民事訴訟法第259條
被告於言詞辯論終結前，得在本訴繫屬之法院，對於原告及就訴訟標的必須合一確定之人提起反訴。