As the final arbiter of the law, the Supreme Court is charged with ensuring the American people the promise of equal justice under law and, thereby, also functions as guardian and interpreter of the Constitution.
The unique position of the Supreme Court stems, in large part, from the deep commitment of the American people to the Rule of Law and to constitutional government.
The United States has demonstrated an unprecedented determination to preserve and protect its written Constitution, thereby providing the American "experiment in democracy" with the oldest written Constitution still in force.
The Constitution of the United States is a carefully balanced document. It is designed to provide for a national government sufficiently strong and flexible to meet the needs of the republic, yet sufficiently limited and just to protect the guaranteed rights of citizens; it permits a balance between society's need for order and the individual's right to freedom.
To assure these ends, the Framers of the Constitution created three independent and coequal branches of government. The continuous democratic government through the periodic stresses of more than two centuries illustrates the success of the American system of government.
The complex role of the Supreme Court in this system derives from its authority to invalidate legislation or executive actions which, in the Court's considered judgment, conflict with the Constitution.
This power of "judicial review" has given the Court a crucial responsibility in assuring individual rights, as well as in maintaining a "living Constitution" whose broad provisions are continually applied to complicated new situations.
Excerpted from: "The Court and Constitutional Interpretation." Supreme Court of the United States. http://www.supremecourtus.gov/