The Constitution gave the Supreme Court the responsibility to uphold the Constitution as the "Supreme Law of the Land," that is, supreme against Federal laws and State laws. Although each State had its own State Constitution and a Judiciary tasked with upholding the Constitution, State laws that violated the Federal Constitution could be overturned by a Federal court.
The Power of the Judiciary Relative the Legislative and Executive Branches
The Framers of the Constitution viewed the Judiciary as a Check on the other two branches, not necessarily as a dynamic force in itself. In the Federalist Paper No. 78, James Madison wrote that "…the judiciary, from the nature of its functions, will always be the least dangerous to the political rights of the Constitution . . . [it] may truly be said to have neither FORCE nor WILL, but merely judgment; and must ultimately depend upon the aid of the executive arm even for the efficacy of its judgments." (Federalist No. 78)
Although the Framers believed that the Judiciary was meant to have a limited role, it did appear, as Justice Marshall implied, that the Supreme Court was meant to be the mouthpiece for the Constitution. "A constitution is, in fact, and must be regarded by the judges, as a fundamental law. It therefore belongs to them to ascertain its meaning, as well as the meaning of any particular act proceeding from the legislative body. If there should happen to be an irreconcilable variance between the two, that which has the superior obligation and validity ought, of course, to be preferred; or, in other words, the Constitution ought to be preferred to the statute, the intention of the people to the intention of their agents." (Federalist No. 78)
The Judiciary and its Relationship with the Popular Electorate
The Judiciary is the only branch of the Federal Government not popularly elected. The Federal Judiciary is appointed by the President, the head of the Executive Branch. The appointment must also gain the approval of Congress before becoming effective. However, at no point in the process does the popular electorate have a say. In a very important sense, the Judiciary can be seen as the least democratic of the three branches of government.
The insulation of the Supreme Court from popular opinion is unsettling when one considers that the Supreme Court has the power to strike down the laws of a popularly elected Congress. This creates the possibility that the popular electorate has no say in a critical phase of the legislative process. For example, if there were a very activist Supreme Court which overturned many laws that were popular with a majority of the electorate, there would be no way for the electorate to remove the Justices on the Supreme Court. This is contrasted with the power of the electorate to remove members of Congress when those members vote for laws which are unpopular with that particular electorate.
Although the notion of a branch of government insulated from the popular electorate sounds undemocratic, it is undemocratic in the context of a pure Democracy. Pure democracies, such as the democracy of ancient Athens, functioned through popular assemblies where citizens would vote yay or nay on initiatives, such as an initiative to raise taxes or go to war. However, the popular assemblies of these pure democracies were vulnerable to manipulation and often made foolish decisions out of fear or anger.
Through the intention of the Framers, the United States is not a pure Democracy, but a Republic. In the context of political philosophy, Republics differ from pure Democracies in that Republics use appointed or elected representatives for certain government functions instead of popular electorate. Republics are meant to curb the worst excesses of pure democracies, arising from the misinformation, self-interest, and short-sightedness of the popular electorate.
The Supreme Court is a distinctly Republican type of institution because it is largely independent of the popular electorate. More importantly, the members of the Federal Judiciary are meant to be selected for their technical competence, not their popularity or political views and affiliations. The Federal Courts are meant to be staffed by expert Jurists, not partisan politicians. In this way, the Supreme Court is designed to look after the integrity and long-term interests of the United States even when the popular electorate, through the other branches of government, isn't.
The power of the Supreme Court today might surprise some of the Framers of the Constitution had they been around to see it. The Supreme Court has great influence on law and policy in the United States. Furthermore, the Supreme Court has become more and more partisan over the years, with unabashedly Liberal Justices and Conservative Justices. Thus, the legacy of Marbury v. Madison is as conspicuous now…