The Supreme Court has original jurisdiction in cases involving ambassadors, other public ministers and consuls, and cases in which a state is a party. Specifically, the Constitution (Article III, Section 2) grants the Supreme Court original jurisdiction over:
- All cases affecting ambassadors, public ministers, and consuls
- Cases in which one or more states are parties
Additionally, under federal statute 28 U.S.C. ยง 1251, the Supreme Court has exclusive original jurisdiction in controversies between two or more states. It also has original but not exclusive jurisdiction in cases such as:
- Actions involving ambassadors or other public ministers and consuls
- Controversies between the United States and a state
- Actions by a state against citizens of another state or against foreigners
In practice, this means the Supreme Court is the first court to hear such cases, rather than hearing them on appeal from lower courts. The Court's original jurisdiction is narrowly defined by the Constitution and cannot be expanded by Congress. Typically, cases under original jurisdiction include disputes between states over boundaries, water rights, and other interstate issues, as well as rare cases involving foreign diplomats or states against the federal government or citizens of other states.
