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 Oregon, the consolidation of lawsuits is governed by the Oregon Rules of Civil Procedure (ORCP), specifically Rule 54, which allows for the consolidation of actions when they involve a common question of law or fact. This rule permits a court to order consolidation for convenience and to avoid unnecessary costs or delay. The decision to consolidate is at the discretion of the court and is typically considered when the actions are before the same court. However, if the actions are pending in different courts, a transfer may be necessary before consolidation can occur. The transfer process would be subject to the jurisdictional rules and procedures of the courts involved. Additionally, federal lawsuits in Oregon may be consolidated in accordance with the Federal Rules of Civil Procedure, Rule 42, which similarly allows for consolidation when actions involve common questions of law or fact. The decision to consolidate federal cases is at the discretion of the federal court. It's important to consult with an attorney to understand the specific circumstances and procedures for consolidation in either state or federal court.