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 Arizona, the consolidation of lawsuits is governed by the Arizona Rules of Civil Procedure. Rule 42(a) allows for the consolidation of actions when they involve a common question of law or fact. 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. This is applicable when the lawsuits are pending in the same court. If the cases are in different courts, a transfer may be necessary before consolidation can occur. The decision to consolidate is at the discretion of the court and is intended to promote efficiency and reduce the possibility of inconsistent verdicts. Additionally, federal cases may be consolidated if they are pending in the same district or can be transferred to another district under certain circumstances as per the Federal Rules of Civil Procedure. It's important to consult with an attorney to understand the specific procedures and implications of consolidation in any given case.