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 New Jersey, the consolidation of lawsuits is governed by the New Jersey Court Rules, specifically Rule 4:38-1, which allows for the consolidation of actions that involve a common question of law or fact. The rule permits a court to order a joint hearing or trial of any or all the matters in issue in the actions; it can also order all the actions consolidated, and it may make such orders concerning proceedings therein as may tend to avoid unnecessary costs or delay. This is applicable when the cases are pending in the same court. If the lawsuits are pending in different courts within New Jersey, a transfer may be necessary before consolidation can occur. The decision to consolidate is at the discretion of the court and is based on the interest of justice and judicial efficiency. At the federal level, Rule 42(a) of the Federal Rules of Civil Procedure provides similar provisions for the consolidation of lawsuits that involve common questions of law or fact, and federal courts have the authority to transfer cases between districts for consolidation under 28 U.S.C. § 1404(a) if it is in the interest of justice and will serve the convenience of parties and witnesses.