The Constitution of the United States of America

By enacting the Constitution of the United States, the citizens consented to the formation of a representative democracy and a federal system of limited central government. The people of the United States share responsibility for good government. The words of the Constitution's Preamble explain it's purpose:
      
We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.