Supplemental Complaint Law and Legal Definition

Supplemental complaint refers to an additional complaint that either corrects a defect in the original complaint or adds relevant matters that occurred after the action began. Generally, a party must obtain the court’s permission to file a supplemental complaint. The usual office of a supplemental complaint is to set up facts occurring subsequent to the filing of the original complaint which justify other or further relief with respect to the same subject matter as the controversy referred to in the complaint. In Brown v. Valley View Mining Co., 127 Cal. 630 (Cal. 1900), it was held that the right to file a supplemental complaint can be exercised only with reference to matters which may be consistent with and in aid of the case made by the original complaint. However, it is not allowable to substitute a new and independent cause of action by way of supplemental complaint.