The American political system is clearly defined by basic documents. The Declaration of Independence of 1776 and the Constitution of 1789 form the foundations of the United States federal government. The Declaration of Independence establishes the United States as an independent political entity, while the Constitution creates the basic structure of the federal government.
The United States Constitution is the shortest written constitution in the world with just seven articles and 27 amendments. The first 10 amendments were all carried in 1789 and are collectively known as the Bill of Rights. If one accepts that these first 10 amendments were in effect part of the original constitutional settlement, there have only been 17 amendments in over 200 years.
One of the major reasons for this relative immutability is that the Constitution is a very difficult instrument to change. First, a proposed amendment has to secure a two-thirds vote of members present in both houses of Congress. Then three-quarters of the state legislatures have to ratify the proposed change.
At the heart of the US Constitution is the principle known as ‘separation of powers’ enlightenment thinker Montesquieu. This means that power is spread between three institutions of the state – the executive, the legislature and the judiciary- and no one institution has too much power and no individual can be a member of more than one institution.
This principle is also known as ‘checks and balances’, since each of the three branches of the state has some authority to act on its own, some authority to regulate the other two branches, and has some of its own authority, in turn, regulated by the other branches.
Not only is power spread between the different branches; the members of those branches are deliberately granted by the Constitution different terms of office which is a further brake on rapid political change. So the President has a term of four years, while members of the Senate serve for six years and members of the House of Representatives serve for two years. Members of the Supreme Court effectively serve for life.
Living Constitution is a concept which claims that the Constitution has a dynamic meaning and that contemporary society should be taken into account when interpreting key constitutional phrases. Instead of seeking to divine the views of the drafters of the document, it claims that they deliberately wrote the Constitution in broad terms so that it would remain flexible.