List of landmark court decisions in the United States

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.

In the United States, landmark court decisions come most frequently from the Supreme Court. United States courts of appeals may also make such decisions, particularly if the Supreme Court chooses not to review the case. Although many cases from state supreme courts are significant in developing the law of that state, only a few are so revolutionary that they announce standards that many other state courts then choose to follow.