Ellis Island is a federally owned island in New York Harbor, situated within the U.S. states of New York and New Jersey, that was the busiest immigrant inspection and processing station in the United States. From 1892 to 1954, nearly 12 million immigrants arriving at the Port of New York and New Jersey were processed there under federal law. Today, it is part of the Statue of Liberty National Monument and is accessible to the public only by ferry. The north side of the island is the site of the main building, now a national museum of immigration. The south side of the island, including the Ellis Island Immigrant Hospital, is open to the public only through guided tours.

In the 19th century, Ellis Island was the site of Fort Gibson and later became a naval magazine. The first inspection station opened in 1892 and was destroyed by fire in 1897. The second station opened in 1900 and housed facilities for medical quarantines and processing immigrants. After 1924, Ellis Island was used primarily as a detention center for migrants. During both World War I and World War II, its facilities were also used by the US military to detain prisoners of war. After the immigration station's closure, the buildings languished for several years until they were partially reopened in 1976. The main building and adjacent structures were completely renovated in 1990.

The 27.5-acre (11.1 ha) island was greatly expanded by land reclamation between the late 1890s and the 1930s. Jurisdictional disputes between New Jersey and New York State persisted until the 1998 US Supreme Court ruling in New Jersey v. New York.

The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate and largely discretionary appellate jurisdiction over all federal and state court cases that involve a point of federal law, and original jurisdiction over a narrow range of cases, specifically "all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party." The Court holds the power of judicial review, the ability to invalidate a statute for violating a provision of the Constitution. It is also able to strike down presidential directives for violating either the Constitution or statutory law. However, it may act only within the context of a case in an area of law over which it has jurisdiction. The Court may decide cases having political overtones but has ruled that it does not have power to decide non-justiciable political questions.

Established by Article Three of the United States Constitution, the composition and procedures of the Supreme Court were initially established by the 1st Congress through the Judiciary Act of 1789. As later set by the Judiciary Act of 1869, the Court consists of the chief justice of the United States and eight associate justices. Each justice has lifetime tenure, meaning they remain on the Court until they die, retire, resign, or are removed from office. When a vacancy occurs, the president, with the advice and consent of the Senate, appoints a new justice. Each justice has a single vote in deciding the cases argued before the Court. When in majority, the chief justice decides who writes the opinion of the court; otherwise, the most senior justice in the majority assigns the task of writing the opinion.

The Court meets in the Supreme Court Building in Washington, D.C. Its law enforcement arm is the Supreme Court Police.