In 1801, during the last weeks of his term as president, Adams appointed several federal judges (the "Midnight Judges"), including Marshall as Chief Justice of the United States on January 20, 1801. One week later, the Senate confirmed his nomination unanimously, and Marshall received his commission on February 4.
The three previous chief justices (John Jay, John Rutledge, and Oliver Ellsworth) had left little permanent mark beyond setting up the forms of office. The Supreme Court, like the state supreme courts, was a minor organ of government. In his 34-year tenure, Marshall made it a third co-equal branch, which it remains today. With his associate justices, especially Joseph Story, William Johnson, and Bushrod Washington, Marshall's Court defined the constitutional standards of the new nation. The great work of the Marshall Court was done in a handful of great cases, especially Marbury v. Madison, McCulloch v. Maryland, Cohens v. Virginia and Gibbons v. Ogden.
His influential rulings reshaped American government, making the Supreme Court the final arbiter of the Constitution—a document with respect to which the Court has the power to overrule the Congress, the president, the states, and all lower courts. He redefined the legal rights of corporations in terms of the individual rights of the stockholders, giving corporations the same level of protection for their property as individuals had. Marshall thereby provided corporations a shield against intrusive state governments. Marshall, along with Daniel Webster (who argued some of the cases), was the leading Federalist of the day, pursuing Federalist approaches to build a stronger federal government over the opposition of the Jeffersonian Republicans, who wanted stronger state governments. Marshall's most important rulings include Cohens v. Virginia, Fletcher v. Peck, Gibbons v. Ogden, Marbury v. Madison, McCulloch v. Maryland, Trustees of Dartmouth College v. Woodward, and Worcester v. Georgia.
Some of his decisions were unpopular; Andrew Jackson went so far as to completely ignore the ruling of Worcester v. Georgia, for example. Nevertheless, Marshall set a great precedent in American politics by being able to balance out the branches of government, and the states and the federal power, providing the rule of law that still prevails.
One of Marshall's most lasting contributions to the Supreme Court was in how opinions are delivered. Before Marshall, opinions were delivered seriatim, meaning each justice delivered a separate opinion. That model is still used by the Supreme Court of the United Kingdom. However, Marshall convinced his colleagues to adopt a single opinion for the court, allowing it to present a clear rule. During his 34 years as Chief Justice he judged over 1,100 cases; he wrote the majority opinion in 519. Marshall was in the dissenting minority only eight times throughout his tenure at the court because of his control over the associate justices. As one observer at the time noted, Marshall had the knack of "putting his own ideas into the minds of others, unconsciously to them".
Marshall had charm, humor, a quick intelligence, and the ability to bring men together. Above all, he had patriotism, sincerity and presence that commanded attention. His opinions were workmanlike, not eloquent in style or subtle; and his learning in the law was not deep. What distinguished him was the force of his intellect, steadfast purpose, and a confident vision of the future greatness he wanted his nation to achieve; these qualities are seen in his historic decisions and gave him the sobriquet, The Great Chief Justice.
 Marbury v. Madison
Marbury v. Madison, decided in 1803, ruled for the government (that is, Madison), by deciding a minor law passed by Congress was unconstitutional. Ironically what was unconstitutional was Congress' granting a certain power to the Supreme Court itself. The case allowed Marshall to proclaim the doctrine of judicial review, which reserves to the Supreme Court final authority to judge whether or not actions of the president or of the Congress are within the powers granted to them by the Constitution. The Constitution itself is the supreme law, and when the Court believes that a specific law or action is in violation of it, the Court must uphold the Constitution and set aside that other law or action.
The Constitution does not explicitly give judicial review to the Court, and Jefferson was very angry with Marshall's position, for he wanted the president to decide whether his acts were constitutional or not. Historians mostly agree that the Founding Fathers Constitution did plan for the Supreme Court to have some sort of judicial review; what Marshall did was make operational their goals. Judicial review was not new and Marshall himself mentioned it in the Virginia ratifying convention of 1788. Marshall's opinion expressed and fixed in the American tradition and legal system a more basic theory—government under law. That is, judicial review means a government in which no person (not even the president) and no institution (not even Congress), nor even a majority of voters, may freely work their will in violation of the written Constitution. Marshall himself never declared another law of Congress or act of a president unconstitutional.
 McCulloch v. Maryland
McCulloch v. Maryland, (1819) was Marshall's second greatest single judicial performance. While it was consistent with Marbury v. Madison, it cuts the other way and prevents states from passing laws that violate the national Constitution. The heart of this opinion is the famous statement, "We must never forget that it is a constitution we are expounding." Marshall laid down the basic theory of implied powers under a written Constitution; a written, but a living, Constitution, intended, as he said "to endure for ages to come, and, consequently, to be adapted to the various crises of human affairs ... ." Marshall envisaged a federal government which, although governed by timeless principles, possessed the plenary powers "on which the welfare of a nation essentially depends." It would be free in its choice of means, not tied to a literal interpretation of the Constitution, and open to change and growth.
 Cohens v. Virginia
Cohens v. Virginia (1821) displayed Marshall's nationalism as he enforced the supremacy of federal law over conflicting state law and overturned the Virginia supreme court. The decision held that the federal judiciary can act directly on private parties and state officials, and has the power to declare and impose on the states the Constitution and federal laws.
 Gibbons v. Ogden
Gibbons v. Ogden (1824) overturned a monopoly granted by the New York state legislature to certain steamships operating between New York and New Jersey. In empowering Congress to regulate interstate commerce, the Constitution automatically deprived the states of the power to obstruct interstate commerce in order to serve their own interests. The long-term impact was ending many state-granted monopolies and promoting free enterprise.
 Other work, later life, legacy
Marshall loved his home, built in 1790, in Richmond, Virginia, and spent as much time there as possible in quiet contentment. While in Richmond he attended St. John's Church in Church Hill until 1814 when he led the movement to hire Robert Mills as architect of Monumental Church, which commemorated the death of 72 Virginians. The Marshall family occupied pew No. 23 at Monumental Church and entertained the Marquis de Lafayette there during his visit to Richmond in 1824. For approximately three months each year; however, he would be away in Washington for the Court's annual term; he would also be away for several weeks to serve on the circuit court in Raleigh, North Carolina.
In 1823, he became first president of the Richmond branch of the American Colonization Society, which was dedicated to resettling freed American slaves in Liberia, on the West coast of Africa. In 1828, he presided over a convention to promote internal improvements in Virginia.
In 1829, he was a delegate to the state constitutional convention, where he was again joined by fellow American statesman and loyal Virginians, James Madison and James Monroe, although all were quite old by that time. Marshall mainly spoke at this convention to promote the necessity of an independent judiciary.
On December 25, 1831, Mary, his beloved wife of some 49 years, died. Most who knew Marshall agreed that after Mary's death, he was never quite the same.
On returning from Washington in the spring of 1835, he suffered severe contusions resulting from an accident to the stage coach in which he was riding. His health, which had not been good for several years, now rapidly declined, and in June he journeyed to Philadelphia, Pennsylvania for medical attendance. There he died on July 6, at the age of 79, having served as Chief Justice for over 34 years. He also was the last surviving member of John Adams's Cabinet and the second to last surviving Founding Father, the last being James Madison.
Two days before his death, he enjoined his friends to place only a plain slab over his and his wife's graves, and he wrote the simple inscription himself. His body, which was taken to Richmond, lies in Shockoe Hill Cemetery in a well kept grave.[2