Keywords: New York, Motion for Leave to File Third Party Complaint, detailed description, types. A "Motion for Leave to File Third Party Complaint" in New York is a legal document that requests permission from the court to add a third party to an ongoing lawsuit. This motion allows a defendant or an original third-party defendant to bring in a new party who may be liable for some or all of the plaintiff's claims. The motion is typically filed when the defendant believes that a non-party (the third party) should be brought into the lawsuit as they might be responsible for part or all of the plaintiff's alleged damages. The New York Motion for Leave to File Third Party Complaint is governed by Rule 3021 of the New York Civil Practice Law and Rules. There are two main types of Motion for Leave to File Third Party Complaint in New York: 1. Imp leader: This type of motion is filed by an original defendant against a third party, seeking to hold the third party partially or solely liable for the plaintiff's claims. The original defendant files the motion to protect themselves from potential liability and may request that the court require the third-party defendant to contribute to any eventual judgment. 2. Derivative Action: In certain cases, when a defendant believes that a third party may be responsible for the plaintiff's claims, but the third party's negligence or fault was caused by another party, they can file a Motion for Leave to File Third Party Complaint for derivative liability. This allows the original defendant to transfer the liability to the third party and hold them responsible for the consequences caused by another party's actions. When filing a Motion for Leave to File Third Party Complaint in New York, it is crucial to include necessary supporting evidence and legal arguments explaining why the addition of the third party is essential for the resolution of the case. The court will evaluate the merits of the motion and determine whether granting leave to file the complaint is justified based on the facts and legal principles presented. In conclusion, a New York Motion for Leave to File Third Party Complaint is a legal mechanism that allows defendants in a lawsuit to bring in third parties who may share liability for the plaintiff's alleged damages. The two main types of this motion are imp leader, where defendants seek to hold a third party liable, and derivative action, where defendants transfer liability to a third party caused by another party's actions. It is essential to follow the guidelines of Rule 3021 of the New York Civil Practice Law and Rules and present strong evidence and arguments when filing such a motion.