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Judicial power

Strike down unconstitutional acts

Courts can declare acts of Congress, the President, and the states unconstitutional and refuse to enforce them. It is the judiciary's heaviest tool and the reason a branch with no army or budget balances the other two.

No clause grants it. Marbury v. Madison (1803) reasoned that judges deciding cases under a written supreme Constitution must refuse to apply laws that conflict with it.

Held by

Every federal court; the Supreme Court has the last word

How it works in practice

Review happens only inside real cases: someone with standingThe requirement that a plaintiff show a concrete, particularized injury, caused by the defendant, that a court can redress. No injury, no case.Read the full definition (opens a new tab) must challenge a law's application, and the ruling binds through precedentA prior decision that guides or controls later cases. Courts must follow decisions of the courts above them; 'stare decisis' is the practice of standing by what was decided.Read the full definition (opens a new tab). Any federal court can hold a law unconstitutional; appeals carry the question up, and a Supreme CourtThe only court the Constitution itself creates. Nine Justices, life tenure, and near-total control over which cases they hear.Read the full definition (opens a new tab) holdingThe part of a decision that resolves the case and binds future courts: the legal rule applied to these facts. Everything else is dicta.Read the full definition (opens a new tab) binds every court. The counterweights are real but slow: new appointments, constitutional amendmentA formal change to the Constitution's text. Twenty-seven have been ratified. An amendment outranks every statute, regulation, and prior court decision.Read the full definition (opens a new tab), and the Court's own restraint doctrines.

The answering checks
The President & SenateChoose every judge who will exercise it.
Congress & the statesCan amend the Constitution to supersede a ruling, as the 11th, 14th, 16th, and 26th Amendments did.
Its own limitsNo advisory opinions, standing requirements, and the political-question doctrine keep courts out of some fights entirely.
Source

Constitution Annotated, Marbury v. Madison

Terms to know: judicial reviewCourts' power to strike down laws and executive acts that violate the Constitution, established by Marbury v. Madison (1803).Read the full definition (opens a new tab) · standingThe requirement that a plaintiff show a concrete, particularized injury, caused by the defendant, that a court can redress. No injury, no case.Read the full definition (opens a new tab) · precedentA prior decision that guides or controls later cases. Courts must follow decisions of the courts above them; 'stare decisis' is the practice of standing by what was decided.Read the full definition (opens a new tab)

Plain-language civic education, not legal advice. The live boundaries of this power are set case by case; the sources above and the constitutional text control.