Consolidation of lawsuits may be ordered by a court when two or more lawsuits involving the same or similar parties (plaintiff and defendant), legal issues, and factual issues are pending in the same court or in different courts in the same jurisdiction (state court system or federal court system). If the lawsuits are pending in different courts one case may be transferred to the other court, and the cases consolidated there.

Laws and rules regarding the consolidation—or transfer and consolidation—of lawsuits vary from state to state and in the federal court system.

In Missouri, the consolidation of lawsuits is governed by Missouri state statutes and court rules. According to Rule 52.05 of the Missouri Rules of Civil Procedure, when actions involving a common question of law or fact are pending before the court, it may order a joint hearing or trial of any or all the matters in issue in the actions, consolidate the actions, or issue any other orders to avoid unnecessary costs or delay. This is applicable when the cases are in the same court. If the lawsuits are pending in different courts within the state, a transfer may be necessary before consolidation can occur. The decision to consolidate is at the discretion of the court and is typically done to promote efficiency and to avoid inconsistent judgments. In the federal system, Rule 42(a) of the Federal Rules of Civil Procedure allows for similar consolidation when cases involve common questions of law or fact. The specific procedures for transferring and consolidating cases may vary and are subject to the strategic decisions of the parties and the determination of the courts involved.