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 Ohio, courts have the authority to consolidate lawsuits when they involve common questions of law or fact to promote efficiency and avoid inconsistent judgments. This is governed by the Ohio Rules of Civil Procedure, specifically Rule 42(A), which allows for consolidation when actions involving a common question of law or fact are pending before the court. The decision to consolidate is at the discretion of the court and is typically done to streamline the legal process and reduce the burden on the parties and the court system. If the lawsuits are pending in different courts within Ohio, a transfer may be necessary to consolidate the cases in one court. The process for transferring and consolidating cases may involve coordination between the courts and adherence to specific procedural rules. Federal courts follow a similar rationale under the Federal Rules of Civil Procedure, Rule 42(a), allowing for consolidation when cases involve common issues. The decision to consolidate is made by a judge who considers the potential benefits of combined proceedings against any inconvenience or unfairness that might result from consolidation.