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 Idaho, the consolidation of lawsuits is governed by the Idaho Rules of Civil Procedure (IRCP), particularly Rule 42(a), which allows for the consolidation of actions involving 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 cases are pending in the same court. If the cases are 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. At the federal level, similar provisions for consolidation are found under Rule 42(a) of the Federal Rules of Civil Procedure. The decision to transfer federal cases for consolidation purposes is also subject to the federal venue and jurisdictional statutes, such as 28 U.S.C. § 1404(a) for change of venue and 28 U.S.C. § 1407 for multidistrict litigation.