The U.S. Supreme Court delivered its decision in the landmark case Miller v. California, establishing the Miller test for determining what is obscene material.

The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that turn on questions of U.S. constitutional or federal law. It also has 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." In 1803, the court asserted itself the power of judicial review, the ability to invalidate a statute for violating a provision of the Constitution via the landmark case Marbury v. Madison. It is also able to strike down presidential directives for violating either the Constitution or statutory law.

The following landmark court decisions in the United States contains landmark court decisions which changed the interpretation of existing law in the United States. Such a decision may settle the law in more than one way:

• establishing a significant new legal principle or concept;
• overturning prior precedent based on its negative effects or flaws in its reasoning;
• distinguishing a new principle that refines a prior principle, thus departing from prior practice without violating the rule of stare decisis;
• establishing a test or a measurable standard that can be applied by courts in future decisions.

Miller v. California, 413 U.S. 15 (1973), was a landmark decision of the U.S. Supreme Court clarifying the legal definition of obscenity as material that lacks "serious literary, artistic, political, or scientific value". The ruling was the origin of the three-part judicial test for determining obscene media content that can be banned by government authorities, which is now known as the Miller test.