In the United States, forum shopping most typically occurs when state and federal courts have concurrent jurisdiction over a claim. State and federal courts have different procedural rules and, in some cases, also use different substantive law. See choice of law. Plaintiffs can use this to their advantage. For example, a plaintiff suing a large corporate defendant might sue in state court, predicting that a local jury would be more sympathetic than a federal jury. Alternatively, a plaintiff might prefer one jurisdiction due to a quirk of its procedural rules or due to its choice of law rule. See state procedural laws; Federal Rules of Civil Procedure.
Sometimes, plaintiffs deliberately structure their state law claims against out-of-state defendants to prevent the out-of-state defendants from removing the case to federal court, which might otherwise have diversity jurisdiction under 28 U.S.C. § 1332. For example, a plaintiff suing a major retailer might sue both the national parent company and its local store. By joining the in-state defendant, the plaintiff prevents federal courts from exercising diversity jurisdiction over the case for lack of complete diversity.
When forum shopping, plaintiffs are not limited to choosing between courts of different states, or state court and federal court. Sometimes, plaintiffs may be able to forum shop between courts in different countries. For a Supreme Court cases involving international forum shopping, see Ruhrgas AG v. Marathon Oil Co., 526 U.S. 574 (1999).
See Civil Procedure.