What was the Supreme Court ruling in Marbury v Madison?

At the end of President John Adams term, he appointed William Marbury to the position of Justice of the Peace. John Marshall, the acting Secretary of the State failed to deliver the commission that would secure William Marbury's appointment. When Thomas Jefferson assumed presidency he told his new Secretary of State to not deliver the commissions.
Justice Marshall wrote the opinion on the case stating that while Marbury was entitled to the commission, the Supreme Court did not authorize the power to enforce Madison to deliver it. Furthermore, Marshall reasoned that the Judiciary Act of 1789 was unconstitutional. He argued that when ordinary laws conflict with the Constitution they must be struck down. In short, Marshall declared that the Constitution is the Supreme law of the land, and the Supreme Court was there to decide what is and what is not constitutional. This case was so vital because Marshall was able to establish the Judicial branch as an equal counterpart to the executive and legislative branches.

The plaintiff in this case was a man who had been given a judicial appointment in the dying days of the Adams Administration. However, the appointment letter was never delivered and the new administration of President Thomas Jefferson refused to honor Marbury's appointment. Marbury took James Madison, the secretary of state, to the Supreme Court in a bid to try to obtain the judicial commission which he believed was rightfully his.
In a landmark judgment, the Supreme Court under Chief Justice Marshall ruled that Marbury was not entitled to his appointment. This was largely a political decision, as the Court was made up of Federalists, who didn't want to give the new Democratic-Republican Administration and Congress an excuse to reduce the Supreme Court's powers.
The Court ruled that the law that had given it jurisdiction in the Marbury case was invalid. In other words, the Court struck down a law that had given it more power. In doing so, however, the Court paradoxically increased its power by unilaterally exercising the right of judicial review, that is the power to strike down legislation as unconstitutional, and that power has remained with the Supreme Court ever since, making Marbury v Madison one of the most important cases in American legal history.
https://www.oyez.org/cases/1789-1850/5us137