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 Michigan, consolidation of lawsuits is governed by the Michigan Court Rules, specifically Rule 2.505. This rule allows for the consolidation of actions when there are common questions of law or fact to promote convenience and avoid prejudice. The court 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. When cases are pending in different courts, a transfer may be possible to consolidate them in one court if it serves the interests of justice and judicial efficiency. The decision to consolidate is at the discretion of the court, which will consider factors such as the risk of inconsistent judgments and the potential for reducing the time and expense of litigation. Federal courts have a similar mechanism under Federal Rule of Civil Procedure 42(a), which allows for consolidation when actions involve a common question of law or fact. The decision to consolidate in either state or federal court is case-specific and depends on the circumstances of the individual lawsuits.