What was the Court's reasoning in Marbury v. Madison?

http://en.wikipedia.org/wiki/Marbury_v._Madison

In Marbury v. Madison, the Supreme Court of the United States established the principle of judicial review, which gives the Court the power to declare acts of Congress unconstitutional. To understand the Court's reasoning in this case, you need some background information.

In 1800, President John Adams, a member of the Federalist Party, lost his bid for re-election to Thomas Jefferson, a Democratic-Republican. In the final days of his presidency, Adams appointed a large number of Federalist judges to various government positions, including William Marbury, who was designated as a Justice of the Peace for the District of Columbia.

However, due to an oversight in the delivery of Marbury's commission, he did not receive it before Thomas Jefferson assumed office as the new President. Marbury then petitioned the Supreme Court to issue a writ of mandamus, which would compel the new Secretary of State, James Madison, to deliver the commission.

Chief Justice John Marshall, a Federalist himself, wrote the Court's unanimous opinion. He first addressed the issue of whether Marbury had a right to his commission, concluding that he did. However, Marshall went on to examine whether the Court had the power to issue a writ of mandamus, as Marbury had requested.

In doing so, Marshall delved into the question of whether the provision of the Judiciary Act of 1789, which granted the Court the authority to issue such writs, was constitutional. He argued that while Congress had the power to create inferior federal courts, it did not have the power to expand the Supreme Court's original jurisdiction beyond what was specified in the Constitution.

Marshall explained that the Constitution was the supreme law of the land, and any law passed by Congress that contradicted it would be invalid. Furthermore, he emphasized the Court's duty to interpret the Constitution and, where necessary, strike down laws that were contrary to it.

In this particular case, Marshall determined that the provision granting the power to issue writs of mandamus exceeded the constitutional limits of Congress's authority. As a result, he held that the provision was not enforceable, making Marbury's request for a writ of mandamus unconstitutional.

By asserting the Court's power of judicial review, Marshall cemented the principle that it is the duty of the judiciary to interpret the law, including the Constitution, and to determine the constitutionality of government actions. This landmark decision, handed down in 1803, established the Court as the ultimate arbiter of constitutional matters, and its principles continue to shape American jurisprudence to this day.