The preface USA "1787 Constitution" only one sentence: We the people of the United States, in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and to ourselves and our posterity the blessings of liberty, for the United States of America and establish this constitution.

   Read USA constitution "in 1787," reads the 4 principles:

   First, the federal system. American constitution USA the federal constitution. The federal government has only limited power to the enumeration in the constitution, while the remaining unlisted power belonged to the states or the people.

   Second, the principle of separation of three rights. USA state power is divided into three parts: legislative power, executive power and judicial power. The three part is independent of power. In theory, the right to equal three, and checks and balances. Each power has limits two other types of abuse of power function. This is a famous modern democratic society the separation of the three powers.

   Third, the principle of the supremacy of constitution. Effect American constitution and laws passed by the Congress is higher than that of all other laws, administrative regulations and provisions. Since 1803 the famous Marbury v. Madison, American federal court system can find the right of unconstitutional. This means that the federal court at all levels can be through the review of legislative law is in conflict with the Constitution and laws, can be declared invalid unconstitutional.

   Fourth, the principle of equality for all. According to the America Fourteenth Amendment to the constitution, everyone has equal access to legal protection of rights. Although American constitution has been revised many times, but "the basic principles of the constitution of 1787" still plays an important role.

   The essence America constitution is: limit the powers of government and protect the freedom of the people.