What is the ruling of Murybury v Madison case?

The ruling in Marbury v. Madison (1803) established the principle of judicial review, which allows the Supreme Court to declare laws and actions of Congress and the executive unconstitutional. The case arose when William Marbury petitioned the Court for a writ of mandamus to compel Secretary of State James Madison to deliver his commission as a justice of the peace. Chief Justice John Marshall ruled that while Marbury was entitled to his commission, the Court did not have the jurisdiction to issue the writ because the law granting it was itself unconstitutional. This landmark decision solidified the role of the judiciary as a co-equal branch of government with the power to check the other branches.