What rulings by the Marshall Court enhanced its own power and that of the federal government?

Prior to the John Marshall era, the Supreme Court of the United States lacked a power which is now central to its functioning: it could not, as it can now, assert that a law passed by Congress was in fact unconstitutional. The Marshall Court asserted this power as a result of the Marbury vs. Madison case, in which Marshall cemented the powers of the Supreme Court by determining that a previous minor law on the court's powers, passed in 1789, was actually unconstitutional. Marshall ruled that the Supreme Court could effectively undo a law passed by Congress if it ran contradictory to the Constitution. The Supreme Court was now the ultimate interpreter of the Constitution.
A second key ruling of the Marshall Court pertained to the rights of the federal government over those of states and was driven by the Congressional charter, in 1816, of the second Bank of the United States. With bad loans being issued by the federal bank, states began to pass their own laws and retreated into their own currency. Ultimately, the Marshall Court ruled that, although the Constitution did not specifically offer Congress the power to create a national bank, this was implied in the idea of a government by the people for the people. Congress had to work in the best interests of the country as a whole, and the court declared:

We admit, as all must admit, that the powers of the government are limited, and that its limits are not to be transcended. But we think the sound construction of the Constitution must allow to the national legislature that discretion, with respect to the means by which the powers it confers are to be carried into execution, which will enable that body to perform the high duties assigned to it, in the manner most beneficial to the people. Let the end be legitimate, let it be within the scope of the Constitution, and all means which are appropriate, which are plainly adapted to that end, which are not prohibited, but consist with the letter and spirit of the Constitution, are constitutional.

Effectively, then, the court declared that Congress did have the power to charter a national bank because it was necessary for true unification of the people and was not prohibited by the Constitution. As such, the rulings of individual states in defiance of the national bank were unconstitutional. This ruling established the power of Congress and the federal government to supersede state laws.
http://supremecourthistory.org/timeline_court_marshall.html

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