The Supreme Court of the United States is the highest court in the United States. It has ultimate (but largely discretionary) appellate jurisdiction over all federal courts and over state court cases involving issues of federal law, and original jurisdiction over a small range of cases. The Court, which meets in the United States Supreme Court Building in Washington, D.C., consists of a chief justice and eight associate justices who are nominated by the President and confirmed by the Senate. Once appointed, justices have life tenure unless they resign, retire, or are removed after impeachment.

Under Chief Justices Jay, Rutledge, and Ellsworth (1789–1801), the Court heard few cases; its first decision was West v. Barnes (1791), a case involving a procedural issue. The Court lacked a home of its own and had little prestige, a situation not helped by the highest-profile case of the era, Chisholm v. Georgia, which was immediately repudiated by the Eleventh Amendment.

The Court's power and prestige waxed during the Marshall Court (1801–1835). Under Marshall, the Court established the principle of judicial review, including specifying itself as the supreme expositor of the Constitution (Marbury v. Madison) and made several important constitutional rulings giving shape and substance to the balance of power between the federal government and the states (prominently, Martin v. Hunter's Lessee, McCulloch v. Maryland and Gibbons v. Ogden).

The United States of America (commonly abbreviated to the United States, the U.S., the USA, America, and the States) is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to the east and Russia to the west, across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories in the Pacific and Caribbean.

At 3.79 million square miles (9.83 million km²) and with over 312 million people, the United States is the third or fourth largest country by total area, and the third largest by both land area and population. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The U.S. economy is the world's largest national economy, with an estimated 2011 GDP of $15.1 trillion (22% of nominal global GDP and over 19% of global GDP at purchasing-power parity). Per capita income is the world's sixth-highest.

A supreme court is the highest court within the hierarchy of many legal jurisdictions. Other descriptions for such courts include court of last resort, instance court, judgment court, apex court, and highest court of appeal. Broadly speaking, the decisions of a supreme court are not subject to further review by any other court.

In a few places, the court named the "Supreme Court" is not in fact the highest court; examples include the Supreme Court of the State of New York and the former Supreme Court of Judicature of England and Wales. Conversely, the highest court in some jurisdictions is not named the "Supreme Court"; for example, the High Court of Australia.

Supreme courts typically function primarily as appellate courts, hearing appeals from decisions of lower trial courts, or from intermediate-level appellate courts.

Some countries have multiple "supreme courts" whose respective jurisdictions have different geographical extents, or which are restricted to particular areas of law. In particular, countries with a federal system of government typically have both a federal supreme court (such as the Supreme Court of the United States), and supreme courts for each member state (such as the Supreme Court of Nevada), with the former having jurisdiction over the latter only to the extent that the federal constitution extends federal law over state law; the US states of Texas and Oklahoma also split the functions of a supreme court between separate courts for criminal and civil cases. Jurisdictions with a civil law system often have a hierarchy of administrative courts separate from the ordinary courts, headed by a supreme administrative court. A number of jurisdictions also follow the "Austrian" model of a separate constitutional court (first developed in the Czechoslovak Constitution of 1920).