Under what conditions can a plaintiff file a supplemental complaint?

A plaintiff can file a supplemental complaint to include additional claims or parties that have arisen after the initial complaint was filed. This is permissible under the rules governing supplemental jurisdiction, which allows for the inclusion of claims that are related to the original action. The primary purpose of a supplemental complaint is to provide a mechanism for addressing new developments in the case without requiring the plaintiff to start a new lawsuit.

This practice is particularly useful in ensuring judicial efficiency and can help avoid the duplication of legal processes that would occur if separate lawsuits were filed for claims arising during the course of the original litigation. It enhances the court's ability to manage related issues in one proceeding, which is beneficial for both the parties involved and the judicial system as a whole.