The U.S. Constitution
The Constitution of the United States is the supreme law of the United States of America. The first three Articles of the Constitution establish the rules and separate powers of the three branches of the federal government: a legislature, the bicameral Congress; an executive branch led by the President; and a federal judiciary headed by the Supreme Court.
Preamble
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 secure the blessings of liberty to ourselves and our posterity, do ordain and establish this Constitution for the United States of America.