For a small set of disputes, cases affecting ambassadors and cases where a state is a party, the Supreme Court is the trial court, not the court of last appeal. In practice this means state-versus-state fights: borders, river water, interstate compacts.
Read the clause itself, verbatim and in plain language, in the in-app Constitution.
The Supreme Court, for a narrow class of cases
A state files directly with the Court, which typically appoints a special master to take evidence and recommend a decree the justices then review. These cases are rare (a handful per decade) but consequential: water allocations for entire regions have been settled this way. Marbury itself turned on this clause, Congress cannot expand the jurisdictionA court's legal authority to hear a case: over the subject matter, the parties, and the territory.Full definition in the glossary the Constitution fixes.
Constitution Annotated, Original Jurisdiction
Terms to know: jurisdictionA court's legal authority to hear a case: over the subject matter, the parties, and the territory.Full definition in the glossary
