Complaint of Co-party: Feasibility of Plaintiff's Litigation against Other Plaintiff and Defendant's Litigation against other Defendant

In order to avoid making conflicting judgements, and to reduce multiplicity of actions and judicial costs, some institutions such as ancillary and related claims have been considered in Iranian law. Nonetheless cross-claim does not exist, that is, whenever there are two or more plaintiffs or defendants, one plaintiff can litigate against co-plaintiff and one defendant can file a lawsuit against co-defendant. Various institutions have been adopted in U.S Federal Rules of Civil Procedure for joinder of claims and permissive or compulsory joinder of parties. Therefore, the drafters have endeavored, by getting away from common law and based on equity, to prevent multiplicity of cases among parties and adjudicating different aspects of same or common issues of law and fact together. One of these mechanisms is cross-claim by witch whenever there are more than one plaintiffs or defendants in action, one plaintiff is able to litigate against the other and a defendant can start a case against co-defendant on the understanding that there is a logical relation between original and cross claims. This article examines the possibility of using this institution in Iranian Law.