What was the significance behind the supreme court decison in Mary vs Madison what did it estiblish?

The Supreme Court decision in Marbury v. Madison (1803) was significant because it established the principle of judicial review, allowing the Court to declare laws unconstitutional. This landmark ruling affirmed the judiciary's role as a co-equal branch of government, ensuring that the Constitution remains the supreme law of the land. It set a crucial precedent for the balance of power among the branches of government and has shaped American constitutional law ever since.